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HTML <base> Added in v2.0.0

Contents

A build-time application of <base> to HTML (without relying on <base>) by modifying a[href], video[src], audio[src], source, img[src], [srcset], and more.

If you want to deploy your project in a different directory without changing the content, Eleventy provides a Path Prefix feature to specify the target directory.

  • via --pathprefix on the command line
  • or via pathPrefix object key in your configuration file return object

Historically, we then recommended to use the provided url filter in your templates to transform any local URL with the path prefix. The downside of this method was that it required you to remember and opt-in every URL transformation in your content!

The New Way: HTML <base> Plugin

With this new plugin, you no longer need to use the url filter in your HTML content. This plugin adds an Eleventy Transform that will modify your HTML output and inject your Path Prefix in your template content.

Play Video: New HTML Base Plugin (Changelog №17) New HTML Base Plugin (Changelog №17) ▶8m32s

Why not use the <base> HTML element?

You can, if you’d like! Some folks have found it to be a bit unreliable and edge-casey. This offers a build-time alternative.

Installation

Added in v2.0.0 This plugin is bundled with Eleventy 2.0 (no extra installation is required). It works with all template languages (via an Eleventy Transform) and some of the advanced usage filters require async-friendly template syntax (Nunjucks, Liquid, and JavaScript).

Open up your Eleventy config file (probably eleventy.config.js) and use addPlugin:

eleventy.config.js
import { EleventyHtmlBasePlugin } from "@11ty/eleventy";

export default function (eleventyConfig) {
	eleventyConfig.addPlugin(EleventyHtmlBasePlugin);
}
module.exports = async function (eleventyConfig) {
	const { EleventyHtmlBasePlugin } = await import("@11ty/eleventy");

	eleventyConfig.addPlugin(EleventyHtmlBasePlugin);
}

You’re only allowed one module.exports in your configuration file, so make sure you only copy the require and the addPlugin lines above!

Expand for full options list
eleventy.config.js
import { EleventyHtmlBasePlugin } from "@11ty/eleventy";

export default function (eleventyConfig) {
	eleventyConfig.addPlugin(EleventyHtmlBasePlugin, {
		// The base URL: defaults to Path Prefix
		baseHref: eleventyConfig.pathPrefix,

		// But you could use a full URL here too:
		// baseHref: "http://example.com/"

		// Comma separated list of output file extensions to apply
		// our transform to. Use `false` to opt-out of the transform.
		extensions: "html",
	});
}
module.exports = async function (eleventyConfig) {
	const { EleventyHtmlBasePlugin } = await import("@11ty/eleventy");

	eleventyConfig.addPlugin(EleventyHtmlBasePlugin, {
		// The base URL: defaults to Path Prefix
		baseHref: eleventyConfig.pathPrefix,

		// But you could use a full URL here too:
		// baseHref: "http://example.com/"

		// Comma separated list of output file extensions to apply
		// our transform to. Use `false` to opt-out of the transform.
		extensions: "html",
	});
}

Usage

For templates that output *.html files, you don’t need to do anything else. The HTML plugin will automatically apply the Path Prefix to URLs in any html file in your output directory.

Advanced Usage

This plugin also provides new filters for you to use these transformations manually. This is useful when you want to use the same functionality but the URL you want to transform is not in one of the HTML elements that get automatically transformed (like an HTML comment <!-- Current page: {{ page.url }} -->).

htmlBaseUrl

Transform a single URL string using the base.

With path prefix set to "/pathprefix/":

Syntax Liquid
{{ "/test/" | htmlBaseUrl }}
=> "/pathprefix/test/"

Relative paths are ignored:

{{ "test/" | htmlBaseUrl }}
=> "test/"

{{ "../test/" | htmlBaseUrl }}
=> "../test/"

Absolute URLs are ignored:

{{ "http://example.com/" | htmlBaseUrl }}
=> "http://example.com/"

With path prefix set to "/pathprefix/":

Syntax Nunjucks
{{ "/test/" | htmlBaseUrl }}
=> "/pathprefix/test/"

Relative paths are ignored:

{{ "test/" | htmlBaseUrl }}
=> "test/"

{{ "../test/" | htmlBaseUrl }}
=> "../test/"

Absolute URLs are ignored:

{{ "http://example.com/" | htmlBaseUrl }}
=> "http://example.com/"

With path prefix set to "/pathprefix/":

Syntax 11ty.js
export default function () {
	return `
${this.htmlBaseUrl("/test/")}
=> "/pathprefix/test/"

Relative paths are ignored:

${this.htmlBaseUrl("test/")}
=> "test/"

${this.htmlBaseUrl("../test/")}
=> "../test/"

Absolute URLs are ignored:

${this.htmlBaseUrl("http://example.com/")}
=> "http://example.com/"
`;
};

With path prefix set to "/pathprefix/":

Syntax 11ty.js
module.exports = function () {
	return `
${this.htmlBaseUrl("/test/")}
=> "/pathprefix/test/"

Relative paths are ignored:

${this.htmlBaseUrl("test/")}
=> "test/"

${this.htmlBaseUrl("../test/")}
=> "../test/"

Absolute URLs are ignored:

${this.htmlBaseUrl("http://example.com/")}
=> "http://example.com/"
`;
};

You can override the baseHref option by passing another argument to the filter with your one-off base value. Note that when you use a full URL as your base href, relative paths are no longer ignored—they are modified using the current page’s URL:

With path prefix set to "/pathprefix/":

Syntax Liquid
{{ "/test/" | htmlBaseUrl: "http://example.com/" }}
=> "http://example.com/pathprefix/test/"

Relative urls are resolved using the current page’s url.
For example, on a page with URL `/my-template/`:

{{ "test/" | htmlBaseUrl: "http://example.com/" }}
=> "http://example.com/pathprefix/my-template/test/"

Absolute URLs are still ignored:

{{ "http://11ty.dev/" | htmlBaseUrl: "http://example.com/" }}
=> "http://11ty.dev/"

With path prefix set to "/pathprefix/":

Syntax Nunjucks
{{ "/test/" | htmlBaseUrl("http://example.com/") }}
=> "http://example.com/pathprefix/test/"

Relative urls are resolved using the current page’s url.
For example, on a page with URL `/my-template/`:

{{ "test/" | htmlBaseUrl("http://example.com/") }}
=> "http://example.com/pathprefix/my-template/test/"

Absolute URLs are still ignored:

{{ "http://11ty.dev/" | htmlBaseUrl("http://example.com/") }}
=> "http://11ty.dev/"

With path prefix set to "/pathprefix/":

Syntax 11ty.js
export default function () {
	return (
		`
${this.htmlBaseUrl("/test/", "http://example.com/")}
=> "http://example.com/pathprefix/test/"

Relative urls are resolved using the current page’s url.
For example, on a page with URL ` /
			my -
		template /
			`:

${this.htmlBaseUrl("test/", "http://example.com/")}
=> "http://example.com/pathprefix/my-template/test/"

Absolute URLs are still ignored:

${this.htmlBaseUrl("http://11ty.dev/", "http://example.com/")}
=> "http://11ty.dev/"`
	);
};

With path prefix set to "/pathprefix/":

Syntax 11ty.cjs
module.exports = function () {
	return (
		`
${this.htmlBaseUrl("/test/", "http://example.com/")}
=> "http://example.com/pathprefix/test/"

Relative urls are resolved using the current page’s url.
For example, on a page with URL ` /
			my -
		template /
			`:

${this.htmlBaseUrl("test/", "http://example.com/")}
=> "http://example.com/pathprefix/my-template/test/"

Absolute URLs are still ignored:

${this.htmlBaseUrl("http://11ty.dev/", "http://example.com/")}
=> "http://11ty.dev/"`
	);
};
transformWithHtmlBase

Transform a block of HTML with posthtml. Applies the above htmlBaseUrl filter to each applicable URL in an HTML block (so the URL transformation rules are the same). Requires an async-friendly template language.

We use this in the RSS plugin to change your content to be absolute URLs for broadest compatibility with various RSS feed readers.

With path prefix set to "/pathprefix/":

Syntax Liquid
{{ '<a href="/test/">Link</a>' | transformWithHtmlBase }}
=> '<a href="/pathprefix/test/">Link</a>'

{{ '<a href="/test/">Link</a>' | transformWithHtmlBase: "http://example.com/" }}
=> '<a href="http://example.com/pathprefix/test/">Link</a>'

Resolving relative URLs (with path prefix still at "/pathprefix/"):

Syntax Liquid
On a page with URL `/my-template/`:

{{ '<a href="test/">Link</a>' | transformWithHtmlBase: "http://example.com/" }}
=> '<a href="http://example.com/pathprefix/my-template/test/">Link</a>'

Override the page URL:

{{ '<a href="test/">Link</a>' | transformWithHtmlBase: "http://example.com/", "/my-other-template/" }}
=> '<a href="http://example.com/pathprefix/my-other-template/test/">Link</a>'

With path prefix set to "/pathprefix/":

Syntax Nunjucks
{{ '<a href="/test/">Link</a>' | transformWithHtmlBase }}
=> '<a href="/pathprefix/test/">Link</a>'

{{ '<a href="/test/">Link</a>' | transformWithHtmlBase("http://example.com/") }}
=> '<a href="http://example.com/pathprefix/test/">Link</a>'

Resolving relative URLs (with path prefix still at "/pathprefix/"):

Syntax Nunjucks
On a page with URL `/my-template/`:

{{ '<a href="test/">Link</a>' | transformWithHtmlBase("http://example.com/") }}
=> '<a href="http://example.com/pathprefix/my-template/test/">Link</a>'

Override the page URL:

{{ '<a href="test/">Link</a>' | transformWithHtmlBase("http://example.com/", "/my-other-template/") }}
=> '<a href="http://example.com/pathprefix/my-other-template/test/">Link</a>'

With path prefix set to "/pathprefix/":

Syntax 11ty.js
export default async function () {
	return `
${await this.transformWithHtmlBase(`<a href="/test/">Link</a>`)}
=> '<a href="/pathprefix/test/">Link</a>'

${await this.transformWithHtmlBase(
	`<a href="/test/">Link</a>`,
	"http://example.com/"
)}
=> '<a href="http://example.com/pathprefix/test/">Link</a>'`;
};

Resolving relative URLs (with path prefix still at "/pathprefix/"):

Syntax 11ty.js
export default async function () {
	return `
On a page with URL "/my-template/":

${await this.transformWithHtmlBase(
	'<a href="test/">Link</a>',
	"http://example.com/"
)}
=> '<a href="http://example.com/pathprefix/my-template/test/">Link</a>'

Override the page URL:

${await this.transformWithHtmlBase(
	'<a href="test/">Link</a>',
	"http://example.com/",
	"/my-other-template/"
)}
=> '<a href="http://example.com/pathprefix/my-other-template/test/">Link</a>''`;
};

With path prefix set to "/pathprefix/":

Syntax 11ty.cjs
module.exports = async function () {
	return `
${await this.transformWithHtmlBase(`<a href="/test/">Link</a>`)}
=> '<a href="/pathprefix/test/">Link</a>'

${await this.transformWithHtmlBase(
	`<a href="/test/">Link</a>`,
	"http://example.com/"
)}
=> '<a href="http://example.com/pathprefix/test/">Link</a>'`;
};

Resolving relative URLs (with path prefix still at "/pathprefix/"):

Syntax 11ty.cjs
module.exports = async function () {
	return `
On a page with URL "/my-template/":

${await this.transformWithHtmlBase(
	'<a href="test/">Link</a>',
	"http://example.com/"
)}
=> '<a href="http://example.com/pathprefix/my-template/test/">Link</a>'

Override the page URL:

${await this.transformWithHtmlBase(
	'<a href="test/">Link</a>',
	"http://example.com/",
	"/my-other-template/"
)}
=> '<a href="http://example.com/pathprefix/my-other-template/test/">Link</a>''`;
};
addPathPrefixToFullUrl

Note that passing a full external URL (e.g. http://example.com/) to htmlBaseUrl will return the URL unchanged. We don’t want to add pathPrefix to external links!

However, if you do want to force addition of pathPrefix to a URL, you can use the addPathPrefixToFullUrl filter.

With path prefix set to "/pathprefix/":

Syntax Liquid
{{ "http://example.com/" | addPathPrefixToFullUrl }}
=> "http://example.com/pathprefix/"

With path prefix set to "/pathprefix/":

Syntax Nunjucks
{{ "http://example.com/" | addPathPrefixToFullUrl }}
=> "http://example.com/pathprefix/"

With path prefix set to "/pathprefix/":

Syntax 11ty.js
export default function () {
	return this.addPathPrefixToFullUrl("http://example.com/");
	// "http://example.com/pathprefix/"
};

With path prefix set to "/pathprefix/":

Syntax 11ty.cjs
module.exports = function () {
	return this.addPathPrefixToFullUrl("http://example.com/");
	// "http://example.com/pathprefix/"
};

Other pages in Official Plugins: