Inline-critical NPM

inline-critical

Inline critical-path css and load the existing stylesheets asynchronously. Existing link tags will also be wrapped in <noscript> so the users with javascript disabled will see the site rendered normally.

Installation

This module is installed via npm:

npm install inline-critical

Example Usage

const inline = require('inline-critical');
const html = fs.readFileSync('test/fixtures/index.html', 'utf8');
const critical = fs.readFileSync('test/fixtures/critical.css', 'utf8');
const inlined = inline(html, critical);

Example Usage ignoring stylesheet per regex

const inline = require('inline-critical');
const html = fs.readFileSync('test/fixtures/index.html', 'utf8');
const critical = fs.readFileSync('test/fixtures/critical.css', 'utf8');

const inlined = inline(html, critical, {
  ignore: [/bootstrap/],
});

CLI

inline-critical works well with standard input. You can either pass in the html

cat index.html | inline-critical critical.css

or just flip things around

cat critical.css | inline-critical index.html

or pass in the file as an option

inline-critical critical.css index.html

without having to worry about the correct order

inline-critical index.html critical.css

Run inline-critical --help to see the list of options.

inline(html, styles, options?)

html is the HTML you want to use to inline your critical styles, or any other styles
styles are the styles you're looking to inline
options is an optional configuration object
- strategy select the preload strategy
- extract will remove the inlined styles from any stylesheets referenced in the HTML
- basePath will be used when extracting styles to find the files references by href attributes
- ignore ignore matching stylesheets when inlining.
- selector defines the element used by loadCSS as a reference for inlining.
- noscript specifies position of noscript fallback ('body' - end of body, 'head' - end of head, false - no noscript)
- replaceStylesheets takes an array of stylesheet hrefs to replace the original links in the document. (Used by critical when you extract uncritical css to a target file)

PreloadStrategy

The mechanism to use for lazy-loading stylesheets. JS indicates that a strategy requires JavaScript (falls back to <noscript>).

default: Move stylesheet links to the end of the document and insert preload meta tags in their place.
"body": Move all external stylesheet links to the end of the document.
"media": Load stylesheets asynchronously by adding media="print" and swap to media="all" once loaded (https://www.filamentgroup.com/lab/load-css-simpler/). JS
"swap": Convert stylesheet links to preloads that swap to rel="stylesheet" once loaded. JS
"polyfill": Inject LoadCSS and use it to load stylesheets. JS