diff --git a/.github/workflows/deploy-pages.yml b/.github/workflows/deploy-pages.yml
index 3b8263d..502a273 100644
--- a/.github/workflows/deploy-pages.yml
+++ b/.github/workflows/deploy-pages.yml
@@ -66,8 +66,8 @@ jobs:
       - name: Test assembler
         run: go -C assembler test ./...
 
-      # Lint covers ESLint and svelte-check; the tests cover the framework-free
-      # modules, including the ASCII fold that has to match the Go parser.
+      # The tests cover the framework-free modules, including the ASCII fold
+      # that has to match the Go parser.
       - name: Test web
         working-directory: web
         run: npm test
diff --git a/CLAUDE.md b/CLAUDE.md
index a6b5962..e640750 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -24,7 +24,8 @@ Add the web checks when frontend files changed:
 (cd web && npm test && npm run lint && npm run build)
 ```
 
-`npm run lint` is ESLint plus `svelte-check`, so it is the type check too.
+`npm run lint` is ESLint. The web app is plain JavaScript — no TypeScript, no
+type-check step.
 
 **Do not run the crawler suite as part of routine verification.** The crawler is
 not part of the build — `data/<id>/` is committed and a crawl only refreshes it
@@ -44,8 +45,8 @@ hashes every real input file. That is the point of it; do not skip it.
   regenerated.** A mismatch is a reader bug until proven otherwise, never a cue
   to refresh the file. `parser/cmd/dumpcells` narrows a failure to the cell.
 - **`ToAscii` filters the literal range U+0300..U+036F, not `unicode.Mn`.** It
-  must match `toAscii` in `web/src/lib/to-ascii.ts`, or accent-insensitive search
-  silently misses rows. `to-ascii.test.ts` pins the pairs both sides must agree
+  must match `toAscii` in `web/src/lib/to-ascii.js`, or accent-insensitive search
+  silently misses rows. `to-ascii.test.js` pins the pairs both sides must agree
   on.
 - **The 2016 files use four different layouts, and detection is per sheet.**
   Two of them publish scores in one column per subject instead of a `DIEM_THI`
diff --git a/README.md b/README.md
index f578951..1fcbda7 100644
--- a/README.md
+++ b/README.md
@@ -37,7 +37,7 @@ Each stage runs on its own and hands its output to the next through the stores.
 
 `datasets.json` is the contract between them. It is JSON because Go and the web
 app both read it and neither needs a dependency to do so; presentation stays in
-`web/src/lib/datasets.ts`, keyed by id, which fails loudly if the two disagree.
+`web/src/lib/datasets.js`, keyed by id, which fails loudly if the two disagree.
 
 The dataset id is one identifier end to end:
 
@@ -86,7 +86,7 @@ Pushing to `main` runs the same steps in
 2. Add `parser/configs/<id>.yml` — sheet mode, column indices, validation
    guards. No SQL; the schema is canonical.
 3. Add an entry to `datasets.json` with its expected row count and size
-4. Add the matching presentation to `CONTENT` in `web/src/lib/datasets.ts`
+4. Add the matching presentation to `CONTENT` in `web/src/lib/datasets.js`
 
 Everything else follows: the assembler, the router and the hub all read the
 registry, and the UI adapts to whichever columns the dataset fills. Steps 3 and 4
diff --git a/docs/data-pipeline.md b/docs/data-pipeline.md
index 1bb9567..518df28 100644
--- a/docs/data-pipeline.md
+++ b/docs/data-pipeline.md
@@ -183,7 +183,7 @@ silently drops 13,720 students** (Hanoi +7,275, HCM +6,445). That is what
 
 The databases are written with 1 KiB pages (`PRAGMA page_size` in
 `parser/internal/writer/writer.go`) because the browser fetches them a page per
-HTTP request. `CHUNK_BYTES` in `web/src/lib/sqlite.svelte.ts` must match.
+HTTP request. `CHUNK_BYTES` in `web/src/lib/sqlite.svelte.js` must match.
 
 | id | Source rows | Skipped | DB rows |
 | --- | --- | --- | --- |
diff --git a/docs/system-architecture.md b/docs/system-architecture.md
index 850804a..fd6d5e3 100644
--- a/docs/system-architecture.md
+++ b/docs/system-architecture.md
@@ -46,7 +46,7 @@ because the assembler is a Go program and the web app is not, and JSON is the
 only format both parse without a dependency.
 
 Presentation — titles, labels, search examples, SQL presets — stays in
-`web/src/lib/datasets.ts`, keyed by id. That file cross-checks the two: a registry
+`web/src/lib/datasets.js`, keyed by id. That file cross-checks the two: a registry
 entry with no content, or content for a dataset that was never built, throws at
 module load rather than rendering a page with no title or a link to a database
 that does not exist.
@@ -125,13 +125,13 @@ No component contains a per-dataset conditional. Two mechanisms do the work:
   self-exclude wherever those languages were not sat.
 
 Anything genuinely per-dataset — title, source, database size, search examples,
-SQL presets — lives in `web/src/lib/datasets.ts`.
+SQL presets — lives in `web/src/lib/datasets.js`.
 
 ## Exam ID formats
 
-`web/src/lib/query-mode.ts` decides whether a query is an exam ID or a name, and
+`web/src/lib/query-mode.js` decides whether a query is an exam ID or a name, and
 is shared by the dataset page and `search-form.svelte` (they previously held
-separate copies and had drifted apart on exactly this rule). `query-mode.test.ts`
+separate copies and had drifted apart on exactly this rule). `query-mode.test.js`
 covers every form in the table below.
 
 | Form | Example | Where |
diff --git a/parser/README.md b/parser/README.md
index 23f57e1..3fea335 100644
--- a/parser/README.md
+++ b/parser/README.md
@@ -41,7 +41,7 @@ reader independently verifiable against a hash oracle.
 
 - `ToAscii` strips combining marks in the literal range U+0300–U+036F rather
   than by Unicode category. That covers every Vietnamese diacritic and must
-  stay identical to `toAscii` in `web/src/lib/to-ascii.ts`, or accent-insensitive
+  stay identical to `toAscii` in `web/src/lib/to-ascii.js`, or accent-insensitive
   search misses rows.
 - Gender is normalised to `Nam`/`Nữ`; the Cần Thơ files write `0`/`1` instead
   and are translated. Anything else becomes NULL.
diff --git a/web/eslint.config.js b/web/eslint.config.js
index 2175062..6378a41 100644
--- a/web/eslint.config.js
+++ b/web/eslint.config.js
@@ -1,12 +1,10 @@
 import js from "@eslint/js";
 import svelte from "eslint-plugin-svelte";
 import globals from "globals";
-import ts from "typescript-eslint";
 import svelteConfig from "./svelte.config.js";
 
-export default ts.config(
+export default [
   js.configs.recommended,
-  ...ts.configs.recommended,
   ...svelte.configs.recommended,
   {
     languageOptions: {
@@ -15,16 +13,11 @@ export default ts.config(
   },
   {
     // Svelte files and rune modules are parsed by svelte-eslint-parser, which
-    // needs the TypeScript parser handed to it for `lang="ts"` blocks.
-    files: ["**/*.svelte", "**/*.svelte.ts", "**/*.svelte.js"],
+    // needs the project's svelte.config.js to resolve aliases and runes.
+    files: ["**/*.svelte", "**/*.svelte.js"],
     languageOptions: {
-      parserOptions: {
-        parser: ts.parser,
-        projectService: true,
-        extraFileExtensions: [".svelte"],
-        svelteConfig,
-      },
+      parserOptions: { svelteConfig },
     },
   },
   { ignores: ["dist/", ".svelte-kit/", "node_modules/"] },
-);
+];
diff --git a/web/tsconfig.json b/web/jsconfig.json
similarity index 63%
rename from web/tsconfig.json
rename to web/jsconfig.json
index 4344710..21df54b 100644
--- a/web/tsconfig.json
+++ b/web/jsconfig.json
@@ -1,14 +1,11 @@
 {
   "extends": "./.svelte-kit/tsconfig.json",
   "compilerOptions": {
-    "allowJs": true,
-    "checkJs": true,
+    "moduleResolution": "bundler",
+    "resolveJsonModule": true,
     "esModuleInterop": true,
     "forceConsistentCasingInFileNames": true,
-    "resolveJsonModule": true,
     "skipLibCheck": true,
-    "sourceMap": true,
-    "strict": true,
-    "moduleResolution": "bundler"
+    "sourceMap": true
   }
 }
diff --git a/web/package-lock.json b/web/package-lock.json
index 5ed552d..6f55121 100644
--- a/web/package-lock.json
+++ b/web/package-lock.json
@@ -16,15 +16,11 @@
         "@sveltejs/kit": "^2.70.2",
         "@sveltejs/vite-plugin-svelte": "^6.2.1",
         "@tailwindcss/vite": "^4.3.3",
-        "@types/sql.js": "^1.4.11",
         "eslint": "^9.39.4",
         "eslint-plugin-svelte": "^3.14.0",
         "globals": "^17.4.0",
         "svelte": "^5.56.9",
-        "svelte-check": "^4.4.3",
         "tailwindcss": "^4.3.3",
-        "typescript": "^5.9.3",
-        "typescript-eslint": "^8.48.2",
         "vite": "^7.1.14",
         "vitest": "^4.1.10"
       }
@@ -1187,16 +1183,6 @@
         }
       }
     },
-    "node_modules/@sveltejs/load-config": {
-      "version": "0.2.3",
-      "resolved": "https://registry.npmjs.org/@sveltejs/load-config/-/load-config-0.2.3.tgz",
-      "integrity": "sha512-VT3qmUb8pRV2QrZjd8iAmtg8lf4W0TIjZbvXtz5MKei/q96teWZgGJyyidJzOjzZzvdq616eSRVeMYIQChUTAQ==",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">= 18.0.0"
-      }
-    },
     "node_modules/@sveltejs/vite-plugin-svelte": {
       "version": "6.2.4",
       "resolved": "https://registry.npmjs.org/@sveltejs/vite-plugin-svelte/-/vite-plugin-svelte-6.2.4.tgz",
@@ -1818,13 +1804,6 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/@types/emscripten": {
-      "version": "1.41.5",
-      "resolved": "https://registry.npmjs.org/@types/emscripten/-/emscripten-1.41.5.tgz",
-      "integrity": "sha512-cMQm7pxu6BxtHyqJ7mQZ2kXWV5SLmugybFdHCBbJ5eHzOo6VhBckEgAT3//rP5FwPHNPeEiq4SmQ5ucBwsOo4Q==",
-      "dev": true,
-      "license": "MIT"
-    },
     "node_modules/@types/estree": {
       "version": "1.0.9",
       "dev": true,
@@ -1835,27 +1814,6 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/@types/node": {
-      "version": "26.2.0",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-26.2.0.tgz",
-      "integrity": "sha512-5IviulTZeRNp2vAJ514cc/HUlY5nZ9fCbq9DMyC52BrhFZACo3nI0R7qBxhQmo/d27NFe96ur/b7Wwxklda+kg==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "undici-types": "~8.3.0"
-      }
-    },
-    "node_modules/@types/sql.js": {
-      "version": "1.4.11",
-      "resolved": "https://registry.npmjs.org/@types/sql.js/-/sql.js-1.4.11.tgz",
-      "integrity": "sha512-QXIx38p2ZThJaK9vP5ZdqdlRe1FG9I8SmCZOS7FHfB/2qPAjZwkL7/vlfPg6N/oWHuuOaGg/P/IRwfP2W0kWVQ==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "@types/emscripten": "*",
-        "@types/node": "*"
-      }
-    },
     "node_modules/@types/trusted-types": {
       "version": "2.0.7",
       "resolved": "https://registry.npmjs.org/@types/trusted-types/-/trusted-types-2.0.7.tgz",
@@ -1863,301 +1821,6 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/@typescript-eslint/eslint-plugin": {
-      "version": "8.67.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/eslint-plugin/-/eslint-plugin-8.67.0.tgz",
-      "integrity": "sha512-Un7Heoyj65NREbKAyIrFxeM143NZpExWmy1Nep4DLeQOeLlTeumPjoNKnBrU5D5moWXbPJgRa5Uwcdu0faVNGQ==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "@eslint-community/regexpp": "^4.12.2",
-        "@typescript-eslint/scope-manager": "8.67.0",
-        "@typescript-eslint/type-utils": "8.67.0",
-        "@typescript-eslint/utils": "8.67.0",
-        "@typescript-eslint/visitor-keys": "8.67.0",
-        "ignore": "^7.0.5",
-        "natural-compare": "^1.4.0",
-        "ts-api-utils": "^2.5.0"
-      },
-      "engines": {
-        "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
-      },
-      "funding": {
-        "type": "opencollective",
-        "url": "https://opencollective.com/typescript-eslint"
-      },
-      "peerDependencies": {
-        "@typescript-eslint/parser": "^8.67.0",
-        "eslint": "^8.57.0 || ^9.0.0 || ^10.0.0",
-        "typescript": ">=4.8.4 <6.1.0"
-      }
-    },
-    "node_modules/@typescript-eslint/eslint-plugin/node_modules/ignore": {
-      "version": "7.0.6",
-      "resolved": "https://registry.npmjs.org/ignore/-/ignore-7.0.6.tgz",
-      "integrity": "sha512-BAg6QkE8W+TuQLrrw0Ugr7HegXduRuuj8/ti2kSOc+jz1dmx8/WNcjr6XGnq5YpDWxFwwaavqD0+jIUOKelTsw==",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">= 4"
-      }
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-    "node_modules/@typescript-eslint/parser": {
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-        "url": "https://github.com/sponsors/isaacs"
-      }
-    },
-    "node_modules/@typescript-eslint/typescript-estree/node_modules/semver": {
-      "version": "7.8.5",
-      "resolved": "https://registry.npmjs.org/semver/-/semver-7.8.5.tgz",
-      "integrity": "sha512-Y7/KDsb8LjooZpwaqGyulO6DQlksgCncchHGk+sZIY4SBvUocMBEFH5Ur1fI4dV+Jvl0w6cjvucaIi40puRioA==",
-      "dev": true,
-      "license": "ISC",
-      "bin": {
-        "semver": "bin/semver.js"
-      },
-      "engines": {
-        "node": ">=10"
-      }
-    },
-    "node_modules/@typescript-eslint/utils": {
-      "version": "8.67.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/utils/-/utils-8.67.0.tgz",
-      "integrity": "sha512-U9D1FdwEWBwok3hxxSdhclMb0twvt9QnjIQ0VfQ1AiX2epnpSgv2ubVDsayOFyY8K6FX+AQ7E0FKWVG3iKsj1A==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "@eslint-community/eslint-utils": "^4.9.1",
-        "@typescript-eslint/scope-manager": "8.67.0",
-        "@typescript-eslint/types": "8.67.0",
-        "@typescript-eslint/typescript-estree": "8.67.0"
-      },
-      "engines": {
-        "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
-      },
-      "funding": {
-        "type": "opencollective",
-        "url": "https://opencollective.com/typescript-eslint"
-      },
-      "peerDependencies": {
-        "eslint": "^8.57.0 || ^9.0.0 || ^10.0.0",
-        "typescript": ">=4.8.4 <6.1.0"
-      }
-    },
-    "node_modules/@typescript-eslint/visitor-keys": {
-      "version": "8.67.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/visitor-keys/-/visitor-keys-8.67.0.tgz",
-      "integrity": "sha512-fkv8dHRDqfGtTHuJeebdrQ7cX6Ad4WAS00rgHh9UGvMycF1mjBfsxry1XsLIFhWZ6Judlh6UdzK+TYlbpCXgnA==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "@typescript-eslint/types": "8.67.0",
-        "eslint-visitor-keys": "^5.0.0"
-      },
-      "engines": {
-        "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
-      },
-      "funding": {
-        "type": "opencollective",
-        "url": "https://opencollective.com/typescript-eslint"
-      }
-    },
-    "node_modules/@typescript-eslint/visitor-keys/node_modules/eslint-visitor-keys": {
-      "version": "5.0.1",
-      "resolved": "https://registry.npmjs.org/eslint-visitor-keys/-/eslint-visitor-keys-5.0.1.tgz",
-      "integrity": "sha512-tD40eHxA35h0PEIZNeIjkHoDR4YjjJp34biM0mDvplBe//mB+IHCqHDGV7pxF+7MklTvighcCPPZC7ynWyjdTA==",
-      "dev": true,
-      "license": "Apache-2.0",
-      "engines": {
-        "node": "^20.19.0 || ^22.13.0 || >=24"
-      },
-      "funding": {
-        "url": "https://opencollective.com/eslint"
-      }
-    },
     "node_modules/@vitest/expect": {
       "version": "4.1.10",
       "resolved": "https://registry.npmjs.org/@vitest/expect/-/expect-4.1.10.tgz",
@@ -2401,22 +2064,6 @@
         "url": "https://github.com/chalk/chalk?sponsor=1"
       }
     },
-    "node_modules/chokidar": {
-      "version": "4.0.3",
-      "resolved": "https://registry.npmjs.org/chokidar/-/chokidar-4.0.3.tgz",
-      "integrity": "sha512-Qgzu8kfBvo+cA4962jnP1KkS6Dop5NS6g7R5LFYJr4b8Ub94PPQXUksCw9PvXoeXPRRddRNC5C1JQUR2SMGtnA==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "readdirp": "^4.0.1"
-      },
-      "engines": {
-        "node": ">= 14.16.0"
-      },
-      "funding": {
-        "url": "https://paulmillr.com/funding/"
-      }
-    },
     "node_modules/clsx": {
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/clsx/-/clsx-2.1.1.tgz",
@@ -3189,16 +2836,6 @@
         "node": "*"
       }
     },
-    "node_modules/mri": {
-      "version": "1.2.0",
-      "resolved": "https://registry.npmjs.org/mri/-/mri-1.2.0.tgz",
-      "integrity": "sha512-tzzskb3bG8LvYGFF/mDTpq3jpI6Q9wc3LEmBaghu+DdCssd1FakN7Bc0hVNmEyGq1bq3RgfkCb3cmQLpNPOroA==",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=4"
-      }
-    },
     "node_modules/mrmime": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/mrmime/-/mrmime-2.0.1.tgz",
@@ -3495,20 +3132,6 @@
         "node": ">=6"
       }
     },
-    "node_modules/readdirp": {
-      "version": "4.1.2",
-      "resolved": "https://registry.npmjs.org/readdirp/-/readdirp-4.1.2.tgz",
-      "integrity": "sha512-GDhwkLfywWL2s6vEjyhri+eXmfH6j1L7JE27WhqLeYzoh/A3DBaYGEj2H/HFZCn/kMfim73FXxEJTw06WtxQwg==",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">= 14.18.0"
-      },
-      "funding": {
-        "type": "individual",
-        "url": "https://paulmillr.com/funding/"
-      }
-    },
     "node_modules/resolve-from": {
       "version": "4.0.0",
       "dev": true,
@@ -3563,19 +3186,6 @@
         "fsevents": "~2.3.2"
       }
     },
-    "node_modules/sade": {
-      "version": "1.8.1",
-      "resolved": "https://registry.npmjs.org/sade/-/sade-1.8.1.tgz",
-      "integrity": "sha512-xal3CZX1Xlo/k4ApwCFrHVACi9fBqJ7V+mwhBsuf/1IOKbBy098Fex+Wa/5QMubw09pSZ/u8EY8PWgevJsXp1A==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "mri": "^1.1.0"
-      },
-      "engines": {
-        "node": ">=6"
-      }
-    },
     "node_modules/set-cookie-parser": {
       "version": "3.1.2",
       "resolved": "https://registry.npmjs.org/set-cookie-parser/-/set-cookie-parser-3.1.2.tgz",
@@ -3705,31 +3315,6 @@
         "node": ">=18"
       }
     },
-    "node_modules/svelte-check": {
-      "version": "4.7.6",
-      "resolved": "https://registry.npmjs.org/svelte-check/-/svelte-check-4.7.6.tgz",
-      "integrity": "sha512-t2scM//ZuVbSY/T2w6FSBw1v9s2NEmh/g+sy1lqtosW5ylBV5AF4wFb1Ts9Kf3MbfPDUDJDZ9L436YT0SPTdvw==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "@jridgewell/trace-mapping": "^0.3.25",
-        "@sveltejs/load-config": "^0.2.3",
-        "chokidar": "^4.0.1",
-        "fdir": "^6.2.0",
-        "picocolors": "^1.0.0",
-        "sade": "^1.7.4"
-      },
-      "bin": {
-        "svelte-check": "bin/svelte-check"
-      },
-      "engines": {
-        "node": ">= 18.0.0"
-      },
-      "peerDependencies": {
-        "svelte": "^4.0.0 || ^5.0.0-next.0",
-        "typescript": "^5.0.0 || ^6.0.0"
-      }
-    },
     "node_modules/svelte-eslint-parser": {
       "version": "1.8.0",
       "resolved": "https://registry.npmjs.org/svelte-eslint-parser/-/svelte-eslint-parser-1.8.0.tgz",
@@ -3847,19 +3432,6 @@
         "node": ">=6"
       }
     },
-    "node_modules/ts-api-utils": {
-      "version": "2.5.0",
-      "resolved": "https://registry.npmjs.org/ts-api-utils/-/ts-api-utils-2.5.0.tgz",
-      "integrity": "sha512-OJ/ibxhPlqrMM0UiNHJ/0CKQkoKF243/AEmplt3qpRgkW8VG7IfOS41h7V8TjITqdByHzrjcS/2si+y4lIh8NA==",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=18.12"
-      },
-      "peerDependencies": {
-        "typescript": ">=4.8.4"
-      }
-    },
     "node_modules/type-check": {
       "version": "0.4.0",
       "dev": true,
@@ -3871,51 +3443,6 @@
         "node": ">= 0.8.0"
       }
     },
-    "node_modules/typescript": {
-      "version": "5.9.3",
-      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.9.3.tgz",
-      "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
-      "dev": true,
-      "license": "Apache-2.0",
-      "bin": {
-        "tsc": "bin/tsc",
-        "tsserver": "bin/tsserver"
-      },
-      "engines": {
-        "node": ">=14.17"
-      }
-    },
-    "node_modules/typescript-eslint": {
-      "version": "8.67.0",
-      "resolved": "https://registry.npmjs.org/typescript-eslint/-/typescript-eslint-8.67.0.tgz",
-      "integrity": "sha512-S2udFs8tCKEKffuJ4TB1idGUZiXdCPGi3IPBGWXarbLQ5UPXORV8QEVzJ4gCRduURMb5EkpNCdjbk0eDIuI8Yg==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "@typescript-eslint/eslint-plugin": "8.67.0",
-        "@typescript-eslint/parser": "8.67.0",
-        "@typescript-eslint/typescript-estree": "8.67.0",
-        "@typescript-eslint/utils": "8.67.0"
-      },
-      "engines": {
-        "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
-      },
-      "funding": {
-        "type": "opencollective",
-        "url": "https://opencollective.com/typescript-eslint"
-      },
-      "peerDependencies": {
-        "eslint": "^8.57.0 || ^9.0.0 || ^10.0.0",
-        "typescript": ">=4.8.4 <6.1.0"
-      }
-    },
-    "node_modules/undici-types": {
-      "version": "8.3.0",
-      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-8.3.0.tgz",
-      "integrity": "sha512-j375ScV60dom+YkPFIfTLcOiPxkN/buHz5GobjLhixFuANaNs3C9l4GmrWqejgXWJ7BbJcFYpTEUkS1Ge8bpZQ==",
-      "dev": true,
-      "license": "MIT"
-    },
     "node_modules/uri-js": {
       "version": "4.4.1",
       "dev": true,
diff --git a/web/package.json b/web/package.json
index fbf0a85..646acc1 100644
--- a/web/package.json
+++ b/web/package.json
@@ -9,7 +9,7 @@
     "build": "vite build",
     "preview": "vite preview",
     "test": "vitest run",
-    "lint": "eslint . && svelte-check --tsconfig ./tsconfig.json"
+    "lint": "eslint ."
   },
   "dependencies": {
     "sql.js-httpvfs": "^0.8.12"
@@ -20,15 +20,11 @@
     "@sveltejs/kit": "^2.70.2",
     "@sveltejs/vite-plugin-svelte": "^6.2.1",
     "@tailwindcss/vite": "^4.3.3",
-    "@types/sql.js": "^1.4.11",
     "eslint": "^9.39.4",
     "eslint-plugin-svelte": "^3.14.0",
     "globals": "^17.4.0",
     "svelte": "^5.56.9",
-    "svelte-check": "^4.4.3",
     "tailwindcss": "^4.3.3",
-    "typescript": "^5.9.3",
-    "typescript-eslint": "^8.48.2",
     "vite": "^7.1.14",
     "vitest": "^4.1.10"
   }
diff --git a/web/src/lib/admission-blocks.ts b/web/src/lib/admission-blocks.js
similarity index 88%
rename from web/src/lib/admission-blocks.ts
rename to web/src/lib/admission-blocks.js
index 98f5142..b99c600 100644
--- a/web/src/lib/admission-blocks.ts
+++ b/web/src/lib/admission-blocks.js
@@ -1,15 +1,3 @@
-import type { Student, SubjectKey } from "./types";
-
-export type AdmissionBlock = { code: string; subjects: SubjectKey[]; label: string };
-export type ComputedBlock = {
-  code: string;
-  label: string;
-  total: number;
-  parts: { key: SubjectKey; score: number }[];
-};
-export type TierKey = "common" | "uncommon" | "rare" | "epic" | "legendary" | "prismatic";
-export type Tier = { key: TierKey; symbol: string; label: string };
-
 // Vietnamese university admission-block ("khối thi") definitions, per Circular
 // 03/2017/TT-BGDĐT. Each block is the sum of exactly 3 subject scores.
 //
@@ -17,7 +5,7 @@ export type Tier = { key: TierKey; symbol: string; label: string };
 // skips any block with a missing subject score, so blocks needing GDCD
 // self-exclude on 2016 rows, and blocks needing a language the candidate did
 // not sit self-exclude row by row.
-export const ADMISSION_BLOCKS: AdmissionBlock[] = [
+export const ADMISSION_BLOCKS = [
   { code: "A00", subjects: ["toan", "vat_ly", "hoa_hoc"],     label: "Toán + Lý + Hóa" },
   { code: "A01", subjects: ["toan", "vat_ly", "tieng_anh"],   label: "Toán + Lý + Anh" },
   { code: "A02", subjects: ["toan", "vat_ly", "sinh_hoc"],    label: "Toán + Lý + Sinh" },
@@ -76,14 +64,13 @@ export const ADMISSION_BLOCKS: AdmissionBlock[] = [
 
 // Returns { code, label, total, parts:[{key,score}] } for every block where
 // the student has scores for all three subjects, sorted by total desc.
-export function computeBlocks(student: Student): ComputedBlock[] {
-  const out: ComputedBlock[] = [];
+export function computeBlocks(student) {
+  const out = [];
   for (const b of ADMISSION_BLOCKS) {
     const parts = b.subjects.map((k) => ({ key: k, score: student[k] }));
     if (parts.some((p) => p.score === null || p.score === undefined)) continue;
-    const whole = parts as { key: SubjectKey; score: number }[];
-    const total = whole.reduce((s, p) => s + p.score, 0);
-    out.push({ code: b.code, label: b.label, total, parts: whole });
+    const total = parts.reduce((s, p) => s + p.score, 0);
+    out.push({ code: b.code, label: b.label, total, parts });
   }
   return out.sort((a, b) => b.total - a.total);
 }
@@ -93,7 +80,7 @@ export function computeBlocks(student: Student): ComputedBlock[] {
 // whatever the other scores are, so that boundary is inclusive while the rest
 // are exclusive upper bounds. Every tier carries a unicode symbol as well as a
 // color, so the meaning is never conveyed by color alone.
-export function scoreTier(score: number | null | undefined): Tier | null {
+export function scoreTier(score) {
   if (score === null || score === undefined) return null;
   if (score <= 1) return { key: "common",      symbol: "·", label: "Điểm liệt" };
   if (score < 5)  return { key: "uncommon",    symbol: "○", label: "Chưa đạt" };
diff --git a/web/src/lib/admission-blocks.test.ts b/web/src/lib/admission-blocks.test.js
similarity index 96%
rename from web/src/lib/admission-blocks.test.ts
rename to web/src/lib/admission-blocks.test.js
index d78f189..8239e6e 100644
--- a/web/src/lib/admission-blocks.test.ts
+++ b/web/src/lib/admission-blocks.test.js
@@ -1,9 +1,8 @@
 import { describe, expect, it } from "vitest";
 import { ADMISSION_BLOCKS, computeBlocks, scoreTier } from "./admission-blocks";
-import type { Student } from "./types";
 
 /** A row with every column NULL, so a test only states the scores it needs. */
-function student(scores: Partial<Student>): Student {
+function student(scores) {
   return {
     so_bao_danh: "49008235",
     ho_ten: "Nguyễn Văn A",
diff --git a/web/src/lib/components/custom-query.svelte b/web/src/lib/components/custom-query.svelte
index d18df0b..dd0734c 100644
--- a/web/src/lib/components/custom-query.svelte
+++ b/web/src/lib/components/custom-query.svelte
@@ -1,29 +1,24 @@
-<script lang="ts">
-  import { formatBytes, isBudgetError, type RemoteDatabase } from "$lib/sqlite.svelte";
-  import type { PresetGroup } from "$lib/types";
+<script>
+  import { formatBytes, isBudgetError } from "$lib/sqlite.svelte";
 
   const MAX_ROWS = 1000;
   const PLACEHOLDER = "Nhập truy vấn SQL...\nVí dụ: SELECT * FROM student WHERE toan >= 9 LIMIT 10";
 
-  let {
-    db,
-    disabled = false,
-    presets = [],
-  }: { db: RemoteDatabase | null; disabled?: boolean; presets?: PresetGroup[] } = $props();
+  let { db, disabled = false, presets = [] } = $props();
 
   // By convention every preset list ends with a "Hệ thống" group whose first
   // query dumps the table schema. See lib/sql-presets.ts.
   const schemaPreset = $derived(presets[presets.length - 1]?.queries[0]);
 
   let sql = $state("");
-  let columns = $state<string[]>([]);
-  let rows = $state<Record<string, unknown>[]>([]);
-  let queryError = $state<string | null>(null);
-  let execTime = $state<string | null>(null);
+  let columns = $state([]);
+  let rows = $state([]);
+  let queryError = $state(null);
+  let execTime = $state(null);
   let running = $state(false);
   let autoRan = false;
 
-  async function execute(queryStr: string) {
+  async function execute(queryStr) {
     const source = db;
     if (!source?.ready) return;
     queryError = null;
@@ -52,7 +47,7 @@
     running = true;
     const start = performance.now();
     try {
-      const result = await source.query<Record<string, unknown>>(finalSql, [], "SQL tab");
+      const result = await source.query(finalSql, [], "SQL tab");
       execTime = (performance.now() - start).toFixed(1);
       rows = result.slice(0, MAX_ROWS);
       columns = rows.length > 0 ? Object.keys(rows[0]) : [];
@@ -68,7 +63,7 @@
     }
   }
 
-  function runPreset(presetSql: string) {
+  function runPreset(presetSql) {
     sql = presetSql;
     void execute(presetSql);
   }
diff --git a/web/src/lib/components/score-table.svelte b/web/src/lib/components/score-table.svelte
index b1b2139..16bbf71 100644
--- a/web/src/lib/components/score-table.svelte
+++ b/web/src/lib/components/score-table.svelte
@@ -1,11 +1,10 @@
-<script lang="ts">
+<script>
   import { scoreTier } from "$lib/admission-blocks";
   import { IDENTITY_COLUMNS, SUBJECTS, hasAnyValue } from "$lib/subjects";
-  import type { Student } from "$lib/types";
 
-  let { results }: { results: Student[] | null } = $props();
+  let { results } = $props();
 
-  function formatScore(val: number | null): string {
+  function formatScore(val) {
     return val === null || val === undefined ? "—" : Number(val).toFixed(2);
   }
 
diff --git a/web/src/lib/components/search-form.svelte b/web/src/lib/components/search-form.svelte
index 453bee3..9e97e74 100644
--- a/web/src/lib/components/search-form.svelte
+++ b/web/src/lib/components/search-form.svelte
@@ -1,28 +1,16 @@
-<script lang="ts">
+<script>
   import { detectMode } from "$lib/query-mode";
 
   const DEBOUNCE_MS = 300;
 
-  let {
-    value = "",
-    onSearch,
-    onClear,
-    disabled = false,
-    examples = [],
-  }: {
-    value?: string;
-    onSearch: (q: string) => void;
-    onClear?: () => void;
-    disabled?: boolean;
-    examples?: string[];
-  } = $props();
+  let { value = "", onSearch, onClear, disabled = false, examples = [] } = $props();
 
   // A writable derived: it follows the owner's value — which is bound to the
   // URL, so a deep link or the clear button flows in — and typing overrides it
   // until the next external change.
   let query = $derived(value);
-  let input = $state<HTMLInputElement | null>(null);
-  let timer: ReturnType<typeof setTimeout> | undefined;
+  let input = $state(null);
+  let timer;
 
   const detected = $derived(detectMode(query));
   const canSearch = $derived(detected.mode === "sbd" || detected.mode === "name");
@@ -45,7 +33,7 @@
     return () => clearTimeout(timer);
   });
 
-  function submit(event: SubmitEvent) {
+  function submit(event) {
     event.preventDefault();
     if (!canSearch) return;
     clearTimeout(timer);
diff --git a/web/src/lib/components/student-detail.svelte b/web/src/lib/components/student-detail.svelte
index 525f08d..33b3456 100644
--- a/web/src/lib/components/student-detail.svelte
+++ b/web/src/lib/components/student-detail.svelte
@@ -1,9 +1,8 @@
-<script lang="ts">
+<script>
   import { computeBlocks, scoreTier } from "$lib/admission-blocks";
   import { SUBJECTS } from "$lib/subjects";
-  import type { Student, SubjectKey } from "$lib/types";
 
-  let { student }: { student: Student } = $props();
+  let { student } = $props();
 
   // Visible legend, so a user does not have to hover tiles to decode the
   // colours. The ranges must stay in step with scoreTier() in
@@ -17,22 +16,22 @@
     { key: "prismatic", symbol: "❖", range: "9-10", label: "Xuất sắc" },
   ];
 
-  let copied = $state<null | "sbd" | "share">(null);
+  let copied = $state(null);
 
   const blocks = $derived(computeBlocks(student));
   const subjects = $derived(
     SUBJECTS.filter((s) => student[s.key] !== null && student[s.key] !== undefined).map((s) => ({
-      key: s.key as SubjectKey,
+      key: s.key,
       label: s.label,
-      score: student[s.key] as number,
+      score: student[s.key],
     })),
   );
 
-  function fmt(n: number | null | undefined): string {
+  function fmt(n) {
     return n === null || n === undefined ? "—" : Number(n).toFixed(2);
   }
 
-  function flash(kind: "sbd" | "share") {
+  function flash(kind) {
     copied = kind;
     setTimeout(() => (copied = null), 1500);
   }
diff --git a/web/src/lib/datasets.ts b/web/src/lib/datasets.js
similarity index 87%
rename from web/src/lib/datasets.ts
rename to web/src/lib/datasets.js
index 713c669..3283cc4 100644
--- a/web/src/lib/datasets.ts
+++ b/web/src/lib/datasets.js
@@ -13,7 +13,6 @@
 import registry from "../../../datasets.json";
 
 import { PRESETS_2016, PRESETS_2017 } from "./sql-presets";
-import type { Dataset, PresetGroup } from "./types";
 
 const SUBTITLE = "Dữ liệu thí sinh toàn quốc · Hỗ trợ truy vấn SQL tùy chỉnh";
 
@@ -25,9 +24,7 @@ const SUBTITLE = "Dữ liệu thí sinh toàn quốc · Hỗ trợ truy vấn SQ
  * (crawler/internal/sources/source_<id>.go); it is duplicated here because a Go
  * module and a Vite app cannot share a constant. Keep the two in step.
  */
-type Content = Omit<Dataset, "id" | "dbSizeMb" | "blurb" | "rows"> & { presets: PresetGroup[] };
-
-const CONTENT: Record<string, Content> = {
+const CONTENT = {
   2016: {
     label: "Kỳ thi 2016",
     title: "Tra cứu điểm thi THPT Quốc gia 2016",
@@ -64,7 +61,7 @@ for (const id of Object.keys(CONTENT)) {
   }
 }
 
-export const DATASETS: Dataset[] = registry.datasets.map((d) => ({
+export const DATASETS = registry.datasets.map((d) => ({
   id: d.id,
   dbSizeMb: d.dbSizeMb,
   rows: d.expectedRows,
@@ -75,7 +72,7 @@ export const DATASETS: Dataset[] = registry.datasets.map((d) => ({
 }));
 
 /** Look up a dataset by the route segment, or undefined for an unknown id. */
-export function datasetById(id: string): Dataset | undefined {
+export function datasetById(id) {
   return DATASETS.find((d) => d.id === id);
 }
 
@@ -83,7 +80,7 @@ export function datasetById(id: string): Dataset | undefined {
  * Site path for a dataset. `base` is SvelteKit's, which carries no trailing
  * slash: pathOf(d, "/thptqg") → "/thptqg/2017/".
  */
-export function pathOf(dataset: Dataset, base: string): string {
+export function pathOf(dataset, base) {
   return `${base}/${dataset.id}/`;
 }
 
@@ -93,6 +90,6 @@ export function pathOf(dataset: Dataset, base: string): string {
  * Uncompressed on purpose: the browser reads byte ranges of it, and a range of
  * a gzip stream is not a range of the database.
  */
-export function dbOf(dataset: Dataset, base: string): string {
+export function dbOf(dataset, base) {
   return `${base}/db/${dataset.id}.sqlite3`;
 }
diff --git a/web/src/lib/query-mode.ts b/web/src/lib/query-mode.js
similarity index 81%
rename from web/src/lib/query-mode.ts
rename to web/src/lib/query-mode.js
index 34ccb0f..9a3af26 100644
--- a/web/src/lib/query-mode.ts
+++ b/web/src/lib/query-mode.js
@@ -18,11 +18,8 @@ const SBD_PATTERN = /^[A-Za-z]{0,4}\d+$/;
 export const MIN_SBD_DIGITS = 3;
 export const MIN_NAME_CHARS = 2;
 
-/** How a query was classified, and the hint shown beneath the field. */
-export type QueryMode = "empty" | "sbd" | "sbd-short" | "name" | "name-short";
-
 /** True when the query looks like an exam ID rather than a name. */
-export function isExamId(query: string): boolean {
+export function isExamId(query) {
   return SBD_PATTERN.test(query.trim());
 }
 
@@ -30,19 +27,20 @@ export function isExamId(query: string): boolean {
  * Normalise an exam ID for lookup. Letter prefixes are stored upper-case, so a
  * user typing "bal000001" still matches. No-op for all-digit IDs.
  */
-export function normaliseExamId(query: string): string {
+export function normaliseExamId(query) {
   return query.trim().toUpperCase();
 }
 
-function digitCount(str: string): number {
+function digitCount(str) {
   return (str.match(/\d/g) ?? []).length;
 }
 
 /**
  * Decide what the user is searching for, and what hint to show beneath the
- * field.
+ * field. Returns `{ mode, hint }` where mode is one of:
+ * empty | sbd | sbd-short | name | name-short.
  */
-export function detectMode(raw: string): { mode: QueryMode; hint: string } {
+export function detectMode(raw) {
   const q = raw.trim();
   if (!q) return { mode: "empty", hint: "Gõ SBD (số báo danh) hoặc họ tên để tìm" };
 
diff --git a/web/src/lib/query-mode.test.ts b/web/src/lib/query-mode.test.js
similarity index 100%
rename from web/src/lib/query-mode.test.ts
rename to web/src/lib/query-mode.test.js
diff --git a/web/src/lib/search.ts b/web/src/lib/search.js
similarity index 82%
rename from web/src/lib/search.ts
rename to web/src/lib/search.js
index b40cf03..d306b56 100644
--- a/web/src/lib/search.ts
+++ b/web/src/lib/search.js
@@ -1,7 +1,5 @@
 import { normaliseExamId } from "./query-mode";
-import type { RemoteDatabase } from "./sqlite.svelte";
 import { toAscii } from "./to-ascii";
-import type { Student } from "./types";
 
 export const MAX_RESULTS = 100;
 
@@ -22,7 +20,7 @@ export const MAX_RESULTS = 100;
  *
  * Every step is an index seek. A search costs a few hundred KB.
  */
-export async function searchByName(db: RemoteDatabase, query: string): Promise<Student[]> {
+export async function searchByName(db, query) {
   const words = tokenise(query);
   if (words.length === 0) return [];
 
@@ -38,7 +36,7 @@ export async function searchByName(db: RemoteDatabase, query: string): Promise<S
     WHERE w.word >= ? AND w.word < ?${filters.length ? " AND " + filters.join(" AND ") : ""}
     LIMIT ${MAX_RESULTS}`;
 
-  return db.query<Student>(
+  return db.query(
     sql,
     [seek, upperBound(seek), ...others.map((w) => `% ${escapeLike(w)}%`)],
     `name ${JSON.stringify(words.join(" "))} seeking ${JSON.stringify(seek)}`,
@@ -46,8 +44,8 @@ export async function searchByName(db: RemoteDatabase, query: string): Promise<S
 }
 
 /** Exact lookup by exam number: a primary-key seek, a few pages. */
-export async function lookupExamId(db: RemoteDatabase, id: string): Promise<Student[]> {
-  return db.query<Student>(
+export async function lookupExamId(db, id) {
+  return db.query(
     "SELECT * FROM student WHERE so_bao_danh = ? LIMIT ?",
     [normaliseExamId(id), MAX_RESULTS],
     `exam id ${JSON.stringify(normaliseExamId(id))}`,
@@ -55,7 +53,7 @@ export async function lookupExamId(db: RemoteDatabase, id: string): Promise<Stud
 }
 
 /** Fold to ASCII and split into words, the same shape name_word was built in. */
-export function tokenise(query: string): string[] {
+export function tokenise(query) {
   return toAscii(query).split(/\s+/).filter(Boolean);
 }
 
@@ -63,7 +61,7 @@ export function tokenise(query: string): string[] {
  * The word whose prefix covers the fewest entries, which is the one worth
  * seeking on. One round trip for all of them.
  */
-async function rarest(db: RemoteDatabase, words: string[]): Promise<string> {
+async function rarest(db, words) {
   if (words.length === 1) return words[0];
 
   const sql = words
@@ -71,7 +69,7 @@ async function rarest(db: RemoteDatabase, words: string[]): Promise<string> {
     .join(" UNION ALL ");
   const params = words.flatMap((w) => [w, w, upperBound(w)]);
 
-  const counts = await db.query<{ word: string; n: number }>(sql, params, "word frequencies");
+  const counts = await db.query(sql, params, "word frequencies");
   let best = words[0];
   let bestN = Infinity;
   for (const { word, n } of counts) {
@@ -88,11 +86,11 @@ async function rarest(db: RemoteDatabase, words: string[]): Promise<string> {
  * that can follow the prefix, which is what turns "starts with" into a range
  * the index can seek.
  */
-function upperBound(prefix: string): string {
+function upperBound(prefix) {
   return prefix + "￿";
 }
 
 /** Escape the LIKE wildcards so a user typing % or _ searches for them. */
-function escapeLike(s: string): string {
+function escapeLike(s) {
   return s.replace(/[\\%_]/g, (c) => `\\${c}`);
 }
diff --git a/web/src/lib/sql-presets.ts b/web/src/lib/sql-presets.js
similarity index 98%
rename from web/src/lib/sql-presets.ts
rename to web/src/lib/sql-presets.js
index 1f1ce15..82cdc73 100644
--- a/web/src/lib/sql-presets.ts
+++ b/web/src/lib/sql-presets.js
@@ -1,5 +1,3 @@
-import type { PresetGroup } from "./types";
-
 /**
  * SQL presets shown in the "Truy vấn SQL" tab, per dataset.
  *
@@ -13,7 +11,7 @@ import type { PresetGroup } from "./types";
  * before the user writes anything.
  */
 
-export const PRESETS_2017: PresetGroup[] = [
+export const PRESETS_2017 = [
   {
     category: "Xếp hạng môn",
     queries: [
@@ -181,7 +179,7 @@ FROM student`,
     ],
   },
 ];
-export const PRESETS_2016: PresetGroup[] = [
+export const PRESETS_2016 = [
   {
     category: "Xếp hạng môn",
     queries: [
diff --git a/web/src/lib/sqlite.svelte.ts b/web/src/lib/sqlite.svelte.js
similarity index 79%
rename from web/src/lib/sqlite.svelte.ts
rename to web/src/lib/sqlite.svelte.js
index f8e33d5..19cdcaa 100644
--- a/web/src/lib/sqlite.svelte.ts
+++ b/web/src/lib/sqlite.svelte.js
@@ -1,4 +1,4 @@
-import { createDbWorker, type SqliteStats, type WorkerHttpvfs } from "sql.js-httpvfs";
+import { createDbWorker } from "sql.js-httpvfs";
 import workerUrl from "sql.js-httpvfs/dist/sqlite.worker.js?url";
 import wasmUrl from "sql.js-httpvfs/dist/sql-wasm.wasm?url";
 
@@ -25,8 +25,9 @@ export const SEARCH_BUDGET_BYTES = 25 * 1024 * 1024;
 /** What the SQL tab gets once the user has accepted the cost of a scan. */
 export const PLAYGROUND_BUDGET_BYTES = 250 * 1024 * 1024;
 
-/** What one query cost over the network. */
-export type QueryCost = { requests: number; bytes: number; ms: number };
+/**
+ * What one query cost over the network: `{ requests, bytes, ms }`.
+ */
 
 /**
  * One remotely-paged database, with the load state the UI needs.
@@ -37,28 +38,27 @@ export type QueryCost = { requests: number; bytes: number; ms: number };
  */
 export class RemoteDatabase {
   ready = $state(false);
-  error = $state<string | null>(null);
+  error = $state(null);
   /** Bytes fetched by this database so far, prefetch included. */
   bytesRead = $state(0);
   /** HTTP range requests issued so far. */
   requests = $state(0);
   /** What the most recent query cost on its own. */
-  lastCost = $state<QueryCost | null>(null);
+  lastCost = $state(null);
 
-  #worker: WorkerHttpvfs | null = null;
-  #opening: Promise<WorkerHttpvfs>;
+  #worker = null;
+  #opening;
   #closed = false;
   // Previous cumulative reading, so a query's own cost is a subtraction.
   #seen = { requests: 0, bytes: 0 };
 
-  constructor(
-    readonly url: string,
-    readonly budgetBytes: number = SEARCH_BUDGET_BYTES,
-  ) {
+  constructor(url, budgetBytes = SEARCH_BUDGET_BYTES) {
+    this.url = url;
+    this.budgetBytes = budgetBytes;
     this.#opening = this.#open();
   }
 
-  async #open(): Promise<WorkerHttpvfs> {
+  async #open() {
     const opened = performance.now();
     try {
       const worker = await createDbWorker(
@@ -90,14 +90,11 @@ export class RemoteDatabase {
    * search actually costs, since the byte count depends on how much the read
    * heads prefetched, not just on the pages the plan needed.
    */
-  async query<T>(sql: string, params: unknown[] = [], label?: string): Promise<T[]> {
+  async query(sql, params = [], label) {
     const worker = this.#worker ?? (await this.#opening);
-    // Comlink erases the generic when it proxies the method across the worker
-    // boundary, so the row type is asserted here rather than inferred.
-    const run = worker.db.query as unknown as (sql: string, ...params: unknown[]) => Promise<T[]>;
     const started = performance.now();
     try {
-      return await run(sql, ...params);
+      return await worker.db.query(sql, ...params);
     } finally {
       await this.#account(worker, label ?? firstLine(sql), performance.now() - started);
     }
@@ -110,12 +107,11 @@ export class RemoteDatabase {
    * counter and resets itself to zero when a query trips the ceiling, so it
    * would under-report exactly when the number matters most.
    */
-  async #account(worker: WorkerHttpvfs, label: string, ms: number) {
-    const read = worker.worker.getStats as unknown as () => Promise<SqliteStats | null>;
-    const stats = await read().catch(() => null);
+  async #account(worker, label, ms) {
+    const stats = await worker.worker.getStats().catch(() => null);
     if (!stats) return;
 
-    const cost: QueryCost = {
+    const cost = {
       requests: stats.totalRequests - this.#seen.requests,
       bytes: stats.totalFetchedBytes - this.#seen.bytes,
       ms,
@@ -146,20 +142,20 @@ export class RemoteDatabase {
 }
 
 /** True when a query failed because it would have exceeded the byte budget. */
-export function isBudgetError(err: unknown): boolean {
+export function isBudgetError(err) {
   return /maxBytesToRead|too much data|exceeded/i.test(message(err));
 }
 
-function message(err: unknown): string {
+function message(err) {
   return err instanceof Error ? err.message : String(err);
 }
 
 /** Enough of a query to recognise it in the console. */
-function firstLine(sql: string): string {
+function firstLine(sql) {
   const line = sql.trim().split("\n")[0];
   return line.length > 70 ? `${line.slice(0, 70)}…` : line;
 }
 
-export function formatBytes(n: number): string {
+export function formatBytes(n) {
   return n < 1024 * 1024 ? `${Math.round(n / 1024)} KB` : `${(n / 1048576).toFixed(1)} MB`;
 }
diff --git a/web/src/lib/subjects.ts b/web/src/lib/subjects.js
similarity index 84%
rename from web/src/lib/subjects.ts
rename to web/src/lib/subjects.js
index 50a6ea1..396990b 100644
--- a/web/src/lib/subjects.ts
+++ b/web/src/lib/subjects.js
@@ -1,5 +1,3 @@
-import type { IdentityKey, Student, SubjectKey } from "./types";
-
 /**
  * The 16 subject columns of the canonical schema, in display order. Mirrors
  * `ScoreFields` in parser/internal/schema/schema.go, and is the single list both
@@ -10,7 +8,7 @@ import type { IdentityKey, Student, SubjectKey } from "./types";
  * years without branching.
  */
 
-export const SUBJECTS: { key: SubjectKey; label: string }[] = [
+export const SUBJECTS = [
   { key: "toan", label: "Toán" },
   { key: "ngu_van", label: "Ngữ văn" },
   { key: "vat_ly", label: "Vật lí" },
@@ -34,12 +32,12 @@ export const SUBJECTS: { key: SubjectKey; label: string }[] = [
  * populates these; the same all-NULL filter that hides unused subjects hides
  * them elsewhere, so no per-dataset conditional is needed.
  */
-export const IDENTITY_COLUMNS: { key: IdentityKey; label: string }[] = [
+export const IDENTITY_COLUMNS = [
   { key: "ten_cum_thi", label: "Cụm thi" },
   { key: "gioi_tinh", label: "GT" },
 ];
 
 /** True when at least one row carries a value for `key`. */
-export function hasAnyValue(rows: Student[], key: SubjectKey | IdentityKey): boolean {
+export function hasAnyValue(rows, key) {
   return rows.some((row) => row[key] !== null && row[key] !== undefined);
 }
diff --git a/web/src/lib/to-ascii.ts b/web/src/lib/to-ascii.js
similarity index 89%
rename from web/src/lib/to-ascii.ts
rename to web/src/lib/to-ascii.js
index d798b9c..d82d2cf 100644
--- a/web/src/lib/to-ascii.ts
+++ b/web/src/lib/to-ascii.js
@@ -12,7 +12,7 @@
  *
  * to-ascii.test.ts pins the pairs both sides have to agree on.
  */
-export function toAscii(str: string): string {
+export function toAscii(str) {
   return str
     .normalize("NFD")
     .replace(/[̀-ͯ]/g, "")
@@ -21,7 +21,7 @@ export function toAscii(str: string): string {
 }
 
 /** True when every character is ASCII, i.e. the query carries no diacritics. */
-export function isAsciiOnly(str: string): boolean {
+export function isAsciiOnly(str) {
   for (let i = 0; i < str.length; i++) {
     if (str.charCodeAt(i) > 127) return false;
   }
diff --git a/web/src/lib/to-ascii.test.ts b/web/src/lib/to-ascii.test.js
similarity index 97%
rename from web/src/lib/to-ascii.test.ts
rename to web/src/lib/to-ascii.test.js
index d1c9548..61917bf 100644
--- a/web/src/lib/to-ascii.test.ts
+++ b/web/src/lib/to-ascii.test.js
@@ -8,7 +8,7 @@ import { isAsciiOnly, toAscii } from "./to-ascii";
  * search silently misses rows. The cases below are the ones
  * parser/internal/transform/transform_test.go pins on the Go side.
  */
-const GO_PARITY: [input: string, want: string][] = [
+const GO_PARITY = [
   ["Nguyễn Bửu Lộc", "nguyen buu loc"],
   ["NGUYỄN THỊ HOA", "nguyen thi hoa"],
   ["Trần Thị Phước An", "tran thi phuoc an"],
diff --git a/web/src/lib/types.ts b/web/src/lib/types.ts
deleted file mode 100644
index 91eb320..0000000
--- a/web/src/lib/types.ts
+++ /dev/null
@@ -1,56 +0,0 @@
-/**
- * The shapes the app shares. `Student` mirrors the 22-column table in
- * parser/internal/schema/schema.go — every column is nullable except the three
- * the schema declares NOT NULL, so a typo in a column name fails the build
- * instead of rendering blank.
- */
-
-export type SubjectKey =
-  | "toan"
-  | "ngu_van"
-  | "vat_ly"
-  | "hoa_hoc"
-  | "sinh_hoc"
-  | "khtn"
-  | "lich_su"
-  | "dia_ly"
-  | "gdcd"
-  | "khxh"
-  | "tieng_anh"
-  | "tieng_phap"
-  | "tieng_nga"
-  | "tieng_duc"
-  | "tieng_nhat"
-  | "tieng_trung";
-
-export type IdentityKey = "ten_cum_thi" | "gioi_tinh";
-
-export type Student = {
-  so_bao_danh: string;
-  ho_ten: string;
-  ho_ten_ascii: string;
-  ngay_sinh: string | null;
-} & { [K in IdentityKey]: string | null } & { [K in SubjectKey]: number | null };
-
-/** A dataset as the interface needs it: registry facts plus presentation. */
-export type Dataset = {
-  id: string;
-  /** Size of the hosted database. Nothing downloads it whole; it is shown so a
-   *  user knows what they are querying into. */
-  dbSizeMb: number;
-  /** Row count from the registry, so the footer never runs COUNT(*) — that
-   *  scans an index and would cost 20 MB over range requests. */
-  rows: number;
-  blurb: string;
-  label: string;
-  title: string;
-  subtitle: string;
-  source: string;
-  examples: string[];
-  presets: PresetGroup[];
-};
-
-export type PresetGroup = {
-  category: string;
-  queries: { label: string; sql: string }[];
-};
diff --git a/web/src/routes/+layout.ts b/web/src/routes/+layout.js
similarity index 100%
rename from web/src/routes/+layout.ts
rename to web/src/routes/+layout.js
diff --git a/web/src/routes/+layout.svelte b/web/src/routes/+layout.svelte
index 801be90..d701e67 100644
--- a/web/src/routes/+layout.svelte
+++ b/web/src/routes/+layout.svelte
@@ -1,4 +1,4 @@
-<script lang="ts">
+<script>
   import "../app.css";
 
   let { children } = $props();
diff --git a/web/src/routes/+page.svelte b/web/src/routes/+page.svelte
index 4a8d6b2..da60c88 100644
--- a/web/src/routes/+page.svelte
+++ b/web/src/routes/+page.svelte
@@ -1,12 +1,11 @@
-<script lang="ts">
+<script>
   import { resolve } from "$app/paths";
   import { DATASETS } from "$lib/datasets";
-  import type { Dataset } from "$lib/types";
 
   // Trailing slash on purpose: each page is prerendered as <id>/index.html, and
   // hitting it without the slash costs a GitHub Pages directory redirect.
   // resolve() still supplies the base path.
-  function hrefOf(dataset: Dataset): string {
+  function hrefOf(dataset) {
     return `${resolve("/[dataset]", { dataset: dataset.id })}/`;
   }
 </script>
diff --git a/web/src/routes/[dataset]/+page.ts b/web/src/routes/[dataset]/+page.js
similarity index 71%
rename from web/src/routes/[dataset]/+page.ts
rename to web/src/routes/[dataset]/+page.js
index 055bd77..b9d5a57 100644
--- a/web/src/routes/[dataset]/+page.ts
+++ b/web/src/routes/[dataset]/+page.js
@@ -1,15 +1,14 @@
 import { error } from "@sveltejs/kit";
 import { DATASETS, datasetById } from "$lib/datasets";
-import type { EntryGenerator, PageLoad } from "./$types";
 
 /**
  * One prerendered page per registered dataset. The registry is the repository
  * root's datasets.json, so a dataset the assembler builds is a page that exists,
  * and one it does not is a 404 at build time rather than a blank page.
  */
-export const entries: EntryGenerator = () => DATASETS.map((d) => ({ dataset: d.id }));
+export const entries = () => DATASETS.map((d) => ({ dataset: d.id }));
 
-export const load: PageLoad = ({ params }) => {
+export const load = ({ params }) => {
   const dataset = datasetById(params.dataset);
   if (!dataset) throw error(404, `Unknown dataset: ${params.dataset}`);
   return { dataset };
diff --git a/web/src/routes/[dataset]/+page.svelte b/web/src/routes/[dataset]/+page.svelte
index ac18283..e77d48e 100644
--- a/web/src/routes/[dataset]/+page.svelte
+++ b/web/src/routes/[dataset]/+page.svelte
@@ -1,4 +1,4 @@
-<script lang="ts">
+<script>
   import { browser } from "$app/environment";
   import { replaceState } from "$app/navigation";
   import { base, resolve } from "$app/paths";
@@ -11,15 +11,14 @@
   import { isExamId } from "$lib/query-mode";
   import { MAX_RESULTS, lookupExamId, searchByName } from "$lib/search";
   import { PLAYGROUND_BUDGET_BYTES, RemoteDatabase, SEARCH_BUDGET_BYTES } from "$lib/sqlite.svelte";
-  import type { Student } from "$lib/types";
 
   let { data } = $props();
   const dataset = $derived(data.dataset);
 
-  let db = $state<RemoteDatabase | null>(null);
-  let results = $state<Student[] | null>(null);
-  let searchError = $state<string | null>(null);
-  let activeTab = $state<"search" | "sql">("search");
+  let db = $state(null);
+  let results = $state(null);
+  let searchError = $state(null);
+  let activeTab = $state("search");
   let sqlWarningOpen = $state(false);
   // Raised once the user has accepted that a hand-written query may fetch a lot.
   let budget = $state(SEARCH_BUDGET_BYTES);
@@ -53,7 +52,7 @@
 
   // Sync the query to ?q= without adding a history entry, so back still leaves
   // the page and a copied URL still reproduces the search.
-  function writeUrlQuery(q: string) {
+  function writeUrlQuery(q) {
     const route = resolve("/[dataset]", { dataset: dataset.id });
     // The target IS resolve()'d; the lint rule cannot see through the template
     // literal that appends the query string.
@@ -61,7 +60,7 @@
     replaceState(q ? `${route}?q=${encodeURIComponent(q)}` : route, page.state);
   }
 
-  async function search(q: string) {
+  async function search(q) {
     const source = db;
     if (!source?.ready) return;
     searchError = null;
@@ -104,13 +103,13 @@
 
   // Global shortcuts: Ctrl+Enter submits the SQL query, "/" focuses the search
   // box unless the user is already typing somewhere.
-  function onKeydown(event: KeyboardEvent) {
+  function onKeydown(event) {
     if (event.key === "Escape" && sqlWarningOpen) {
       declineSqlWarning();
       return;
     }
     if (event.ctrlKey && event.key === "Enter" && activeTab === "sql") {
-      document.querySelector<HTMLFormElement>(".query-form")?.requestSubmit();
+      document.querySelector(".query-form")?.requestSubmit();
       return;
     }
     if (
@@ -211,6 +210,8 @@
   <footer class="mt-12 border-t border-line pt-4 text-center text-sm break-words text-ink-subtle">
     <p>
       Nguồn:
+      <!-- An off-site article URL, so there is no route for resolve() to take. -->
+      <!-- eslint-disable-next-line svelte/no-navigation-without-resolve -->
       <a href={dataset.source} target="_blank" rel="noopener noreferrer">{dataset.source}</a>
       · {dataset.rows.toLocaleString("vi-VN")} thí sinh · Dữ liệu chỉ mang tính tham khảo
     </p>
diff --git a/web/vite.config.ts b/web/vite.config.js
similarity index 90%
rename from web/vite.config.ts
rename to web/vite.config.js
index 10313c9..3ad296e 100644
--- a/web/vite.config.ts
+++ b/web/vite.config.js
@@ -7,6 +7,6 @@ export default defineConfig({
   test: {
     // Only the framework-free modules are unit-tested: score tiers, query-mode
     // classification and the ASCII fold that has to match the Go parser.
-    include: ["src/lib/**/*.test.ts"],
+    include: ["src/lib/**/*.test.js"],
   },
 });