Make relURL and related functions consistent (#1895)

This addresses changes made in:
https://github.com/gohugoio/hugo/pull/10002

Closes #469

content/en/functions/abslangurl.md

@@ -1,27 +1,61 @@
 ---
 title: absLangURL
-description: Adds the absolute URL with correct language prefix according to site configuration for multilingual.
+description: Returns an absolute URL with a language prefix, if any.
-date: 2017-02-01
-publishdate: 2017-02-01
-lastmod: 2017-02-01
 categories: [functions]
 menu:
   docs:
-    parent: "functions"
+    parent: functions
-keywords: [multilingual,i18n,urls]
+keywords: [urls, multilingual,i18n]
 signature: ["absLangURL INPUT"]
-workson: []
-hugoversion:
-relatedfuncs: [relLangURL]
-deprecated: false
-aliases: []
 ---
 
-Both `absLangURL` and [`relLangURL`](/functions/rellangurl/) are similar to their [`absURL`](/functions/absurl/) and [`relURL`](/functions/relurl) relatives but will add the correct language prefix when the site is configured with more than one language.
+Use this function with both monolingual and multilingual configurations. The URL returned by this function depends on:
 
-So for a site  `baseURL` set to `https://example.com/hugo/` and the current language is `en`:
+- Whether the input begins with a slash
+- The `baseURL` in site configuration
+- The language prefix, if any
 
+In examples that follow, the project is multilingual with content in both Español (`es`) and English (`en`). The default language is Español. The returned values are from the English site.
+
+### Input does not begin with a slash
+
+If the input does not begin with a slash, the resulting URL will be correct regardless of the `baseURL`.
+
+With `baseURL = https://example.org/`
+
+```go-html-template
+{{ absLangURL "" }}           →   https://example.org/en/
+{{ absLangURL "articles" }}   →   https://example.org/en/articles
+{{ absLangURL "style.css" }}  →   https://example.org/en/style.css
 ```
-{{ "blog/" | absLangURL }} → "https://example.com/hugo/en/blog/"
+
-{{ "blog/" | relLangURL }} → "/hugo/en/blog/"
+With `baseURL = https://example.org/docs/`
+
+```go-html-template
+{{ absLangURL "" }}           →   https://example.org/docs/en/
+{{ absLangURL "articles" }}   →   https://example.org/docs/en/articles
+{{ absLangURL "style.css" }}  →   https://example.org/docs/en/style.css
 ```
+
+### Input begins with a slash
+
+If the input begins with a slash, the resulting URL will be incorrect when the `baseURL` includes a subdirectory. With a leading slash, the function returns a URL relative to the protocol+host section of the `baseURL`.
+
+With `baseURL = https://example.org/`
+
+```go-html-template
+{{ absLangURL "/" }}          →   https://example.org/en/
+{{ absLangURL "/articles" }}  →   https://example.org/en/articles
+{{ absLangURL "/style.css" }} →   https://example.org/en/style.css
+```
+
+With `baseURL = https://example.org/docs/`
+
+```go-html-template
+{{ absLangURL "/" }}          →   https://example.org/en/
+{{ absLangURL "/articles" }}  →   https://example.org/en/articles
+{{ absLangURL "/style.css" }} →   https://example.org/en/style.css
+
+{{% note %}}
+The last three examples are not desirable in most situations. As a best practice, never include a leading slash when using this function.
+{{% /note %}}

content/en/functions/absurl.md

@@ -1,50 +1,61 @@
 ---
 title: absURL
-description: Creates an absolute URL based on the configured baseURL.
+description: Returns an absolute URL.
-date: 2017-02-01
-publishdate: 2017-02-01
-lastmod: 2017-02-01
 categories: [functions]
 menu:
   docs:
-    parent: "functions"
+    parent: functions
 keywords: [urls]
 signature: ["absURL INPUT"]
-workson: []
-hugoversion:
-relatedfuncs: [relURL]
-deprecated: false
-aliases: []
 ---
 
-Both `absURL` and `relURL` consider the configured value of `baseURL` in your site's [`config` file][configuration]. Given a `baseURL` set to `https://example.com/hugo/`:
+With multilingual configurations, use the [`absLangURL`] function instead.  The URL returned by this function depends on:
 
-```
+- Whether the input begins with a slash
-{{ "mystyle.css" | absURL }} → "https://example.com/hugo/mystyle.css"
+- The `baseURL` in site configuration
-{{ "mystyle.css" | relURL }} → "/hugo/mystyle.css"
+
-{{ "http://gohugo.io/" | relURL }} →  "http://gohugo.io/"
+### Input does not begin with a slash
-{{ "http://gohugo.io/" | absURL }} →  "http://gohugo.io/"
+
+If the input does not begin with a slash, the resulting URL will be correct regardless of the `baseURL`.
+
+With `baseURL = https://example.org/`
+
+```go-html-template
+{{ absURL "" }}           →   https://example.org/
+{{ absURL "articles" }}   →   https://example.org/articles
+{{ absURL "style.css" }}  →   https://example.org/style.css
 ```
 
-The last two examples may look strange but can be very useful. For example, the following shows how to use `absURL` in [JSON-LD structured data (SEO)][jsonld], where some of your images for a piece of content may or may not be hosted locally:
+With `baseURL = https://example.org/docs/`
 
-{{< code file="layouts/partials/schemaorg-metadata.html" download="schemaorg-metadata.html" >}}
+```go-html-template
-<script type="application/ld+json">
+{{ absURL "" }}           →   https://example.org/docs/
-{
+{{ absURL "articles" }}   →   https://example.org/docs/articles
-    "@context" : "http://schema.org",
+{{ absURL "style.css" }}  →   https://example.org/docs/style.css
-    "@type" : "BlogPosting",
+```
-    "image" : {{ apply .Params.images "absURL" "." }}
-}
-</script>
-{{< /code >}}
 
-The above uses the [apply function][] and also exposes how the Go template parser JSON-encodes objects inside `<script>` tags. See [the safeJS template function][safejs] for examples of how to tell Hugo not to escape strings inside such tags.
+### Input begins with a slash
 
-{{% note "Ending Slash" %}}
+If the input begins with a slash, the resulting URL will be incorrect when the `baseURL` includes a subdirectory. With a leading slash, the function returns a URL relative to the protocol+host section of the `baseURL`.
-`absURL` and `relURL` are smart about missing slashes, but they will *not* add a closing slash to a URL if it is not present.
+
+With `baseURL = https://example.org/`
+
+```go-html-template
+{{ absURL "/" }}          →   https://example.org/
+{{ absURL "/articles" }}  →   https://example.org/articles
+{{ absURL "/style.css" }} →   https://example.org/style.css
+```
+
+With `baseURL = https://example.org/docs/`
+
+```go-html-template
+{{ absURL "/" }}          →   https://example.org/
+{{ absURL "/articles" }}  →   https://example.org/articles
+{{ absURL "/style.css" }} →   https://example.org/style.css
+```
+
+{{% note %}}
+The last three examples are not desirable in most situations. As a best practice, never include a leading slash when using this function.
 {{% /note %}}
 
-[apply function]: /functions/apply/
+[`absLangURL`]: /functions/abslangurl/
-[configuration]: /getting-started/configuration/
-[jsonld]: https://developers.google.com/search/docs/guides/intro-structured-data
-[safejs]: /functions/safejs

content/en/functions/relLangURL.md

@@ -1,29 +1,62 @@
 ---
 title: relLangURL
-description: Adds the relative URL with correct language prefix according to site configuration for multilingual.
+description: Returns a relative URL with a language prefix, if any.
-date: 2017-02-01
-publishdate: 2017-02-01
-lastmod: 2017-02-01
-keywords: [multilingual,i18n,urls]
 categories: [functions]
 menu:
   docs:
-    parent: "functions"
+    parent: functions
+keywords: [urls, multilingual,i18n]
 signature: ["relLangURL INPUT"]
-workson: []
-hugoversion:
-relatedfuncs: []
-deprecated: false
-aliases: []
 ---
 
-`absLangURL` and `relLangURL` functions are similar to their [`absURL`](/functions/absurl/) and [`relURL`](/functions/relurl/) relatives but will add the correct language prefix when the site is configured with more than one language. (See [Configure Languages][multiliconfig].)
+Use this function with both monolingual and multilingual configurations. The URL returned by this function depends on:
 
-So for a site  `baseURL` set to `https://example.com/hugo/` and the current language is `en`:
+- Whether the input begins with a slash
+- The `baseURL` in site configuration
+- The language prefix, if any
 
-```
+In examples that follow, the project is multilingual with content in both Español (`es`) and English (`en`). The default language is Español. The returned values are from the English site.
-{{ "blog/" | absLangURL }} → "https://example.com/hugo/en/blog/"
+
-{{ "blog/" | relLangURL }} → "/hugo/en/blog/"
+### Input does not begin with a slash
+
+If the input does not begin with a slash, the resulting URL will be correct regardless of the `baseURL`.
+
+With `baseURL = https://example.org/`
+
+```go-html-template
+{{ relLangURL "" }}           →   /en/
+{{ relLangURL "articles" }}   →   /en/articles
+{{ relLangURL "style.css" }}  →   /en/style.css
+``` 
+
+With `baseURL = https://example.org/docs/`
+
+```go-html-template
+{{ relLangURL "" }}           →   /docs/en/
+{{ relLangURL "articles" }}   →   /docs/en/articles
+{{ relLangURL "style.css" }}  →   /docs/en/style.css
 ```
 
-[multiliconfig]: /content-management/multilingual/#configure-languages
+### Input begins with a slash
+
+If the input begins with a slash, the resulting URL will be incorrect when the `baseURL` includes a subdirectory. With a leading slash, the function returns a URL relative to the protocol+host section of the `baseURL`.
+
+With `baseURL = https://example.org/`
+
+```go-html-template
+{{ relLangURL "/" }}          →   /en/
+{{ relLangURL "/articles" }}  →   /en/articles
+{{ relLangURL "/style.css" }} →   /en/style.css
+``` 
+
+With `baseURL = https://example.org/docs/`
+
+```go-html-template
+{{ relLangURL "/" }}          →   /en/
+{{ relLangURL "/articles" }}  →   /en/articles
+{{ relLangURL "/style.css" }} →   /en/style.css
+```
+
+{{% note %}}
+The last three examples are not desirable in most situations. As a best practice, never include a leading slash when using this function.
+{{% /note %}}

content/en/functions/relurl.md

@@ -1,49 +1,61 @@
 ---
 title: relURL
-description: Creates a baseURL-relative URL.
+description: Returns a relative URL.
-date: 2017-02-01
-publishdate: 2017-02-01
 categories: [functions]
 menu:
   docs:
-    parent: "functions"
+    parent: functions
 keywords: [urls]
 signature: ["relURL INPUT"]
-workson: []
-hugoversion:
-relatedfuncs: [absURL]
-deprecated: false
-aliases: []
 ---
 
-Both `absURL` and `relURL` consider the configured value of `baseURL` in your site's [`config` file][configuration]. Given a `baseURL` set to `https://example.com/hugo/`:
+With multilingual configurations, use the [`relLangURL`] function instead. The URL returned by this function depends on:
 
-```
+- Whether the input begins with a slash
-{{ "mystyle.css" | absURL }} → "https://example.com/hugo/mystyle.css"
+- The `baseURL` in site configuration
-{{ "mystyle.css" | relURL }} → "/hugo/mystyle.css"
+
-{{ "http://gohugo.io/" | relURL }} →  "http://gohugo.io/"
+### Input does not begin with a slash
-{{ "http://gohugo.io/" | absURL }} →  "http://gohugo.io/"
+
+If the input does not begin with a slash, the resulting URL will be correct regardless of the `baseURL`.
+
+With `baseURL = https://example.org/`
+
+```go-html-template
+{{ relURL "" }}           →   /
+{{ relURL "articles" }}   →   /articles
+{{ relURL "style.css" }}  →   /style.css
 ```
 
-The last two examples may look strange but can be very useful. For example, the following shows how to use `absURL` in [JSON-LD structured data for SEO][jsonld] where some of your images for a piece of content may or may not be hosted locally:
+With `baseURL = https://example.org/docs/`
 
-{{< code file="layouts/partials/schemaorg-metadata.html" download="schemaorg-metadata.html" >}}
+```go-html-template
-<script type="application/ld+json">
+{{ relURL "" }}           →   /docs/
-{
+{{ relURL "articles" }}   →   /docs/articles
-    "@context" : "https://schema.org",
+{{ relURL "style.css" }}  →   /docs/style.css
-    "@type" : "BlogPosting",
+```
-    "image" : {{ apply .Params.images "absURL" "." }}
-}
-</script>
-{{< /code >}}
 
-The above uses the [apply function][] and also exposes how the Go template parser JSON-encodes objects inside `<script>` tags. See [the safeJS template function][safejs] for examples of how to tell Hugo not to escape strings inside of such tags.
+### Input begins with a slash
 
-{{% note "Ending Slash" %}}
+If the input begins with a slash, the resulting URL will be incorrect when the `baseURL` includes a subdirectory. With a leading slash, the function returns a URL relative to the protocol+host section of the `baseURL`.
-`absURL` and `relURL` are smart about missing slashes, but they will *not* add a closing slash to a URL if it is not present.
+
+With `baseURL = https://example.org/`
+
+```go-html-template
+{{ relURL "/" }}          →   /
+{{ relURL "/articles" }}  →   /articles
+{{ relURL "style.css" }}  →   /style.css
+```
+
+With `baseURL = https://example.org/docs/`
+
+```go-html-template
+{{ relURL "/" }}          →   /
+{{ relURL "/articles" }}  →   /articles
+{{ relURL "/style.css" }} →   /style.css
+```
+
+{{% note %}}
+The last three examples are not desirable in most situations. As a best practice, never include a leading slash when using this function.
 {{% /note %}}
 
-[apply function]: /functions/apply/
+[`relLangURL`]: /functions/rellangurl/
-[configuration]: /getting-started/configuration/
-[jsonld]: https://developers.google.com/search/docs/advanced/structured-data/intro-structured-data
-[safejs]: /functions/safejs