All inline

Inline javascript, stylesheets, and images from an HTML page.

This library is agnostic to how the assets are loaded, allowing it to be used in the browser or with nodejs.

The following HTML elements and CSS data types are inlined:

• Scripts
• Linked CSS stylesheets
• Images, videos, and audio
• Iframes
• CSS url() data types (in <style> element and style attribute)
• Imported stylesheets through @import

Installation

npm i all-inline

Usage

import allInline from "all-inline";

// NodeJS specific libraries, not needed for the browser.
import { JSDOM } from "jsdom";
import mime from "mime-types";
import fs from "fs/promises";

const dom = new JSDOM(`
    <script src="main.js"></script>
    <link rel="stylesheet" href="main.css">
    <style>div { background-image: url('path/to/file'); }</style>
    <div style="background-image: url('path/to/file');"></div>
    <img src="path/to/file">
    <video><source src="path/to/file" type="video/mp4"></video>
    <iframe src="path/to/file"></iframe>
`);

await allInline(dom.window.document, async (src, type) => {
    if (type === 'text') {
        return await fs.readFile(src, 'utf8');
    }
    
    const mimeType = mime.lookup(src) || 'application/octet-stream';
    const encoding = 'base64';
    const data = await fs.readFile(src, encoding);
    return `data:${mimeType};${encoding},${data}`;
});

console.log(dom.serialize());
/*
    <script>const a = 1;</script>
    <style>@font-face { src: url('data:...'); }</style>
    <style>div { background-image: url('data:...'); }</style>
    <div style="background-image: url('data:...');"></div>
    <img src="data:...">
    <video><source src="data:..." type="video/mp4"></video>
    <iframe srcdoc="..."></iframe>
*/

Arguments

Document

The function takes a DOM Document or Element as first argument. If an element is passed, only the children are modified.

Callback

The callback should have 2 arguments src and type.

• The src argument is the path to the file.
• The type argument can be either "text" or "data-uri". The callback should throw an error if the file is binary and text is required.

The callback must return the contents of the file as string. Either as plain text or encoded as data-uri (depending on the type argument). If the callback returns null, inlining that element will be skipped.

Notes

Relative paths in CSS

For CSS, relative paths are automatically prefixed with the path of the css file.

/* my/path/style.css */
body {
  background-image: url(bg.jpg);
}

The read function will be called as

read('my/path/bg.jpg', 'data-uri');

Inline iframe

The HTML contents for iframes is inlined as-is. You might need to apply all-inline to the contents in the read callback.

import { default as allInline, wrapRead } from "all-inline";

async function read(src, type) {
    if (src.endsWith('.html')) {
        const contents = await fs.readFile(src, 'utf8');
        const dom = new JSDom(contents);
        
        await allInline(dom.window.document, wrapRead(src, read));
        return dom.serialize();
    }
    
    //...
}

await allInline(dom.window.document, read);

In the browser, use DomParser instead of JSDom to get a DOM Document object from the HTML content.

External resources

The src argument of the read callback can be a local path or a URL. You should throw an error if loading external resources isn't supported.

async function read(src, type) {
    if (src.match(/^\w+:\/\//)) throw Error(`Unable to load external resource: ${src}`);
    
    // ...
}