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    7.2.0 • Public • Published

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    Inline and compress tags that contain the inline attribute. Supports <script>, <link>, and <img> (including *.svg sources) tags by default, and is easily extensible to handle others.

    NOTE: since version 6, the API is now Promise based, and compatible with async/await, requiring a minimum Node version of 7.6

    You can use inline-source-cli to run inline-source from the command line or NPM Scripts.


    inlineSource(htmlpath, [options]): Promise<string>: parse htmlpath content for tags containing an inline attribute, and replace with (optionally compressed) file contents.

    htmlpath can be either a filepath or a string of html content.

    Available options include:

    • attribute: attribute used to parse sources (all tags will be parsed if set to false. Default 'inline')
    • compress: enable/disable compression of inlined content (default true)
    • fs: specify fs implementation (default is Node core 'fs')
    • handlers: specify custom handlers (default []) [see custom handlers]
    • preHandlers: specify custom pre handlers (default []) [see custom pre handlers]
    • ignore: disable inlining based on tag, type, and/or format (default [])
    • pretty: maintain leading whitespace when options.compress is false (default false)
    • rootpath: directory path used for resolving inlineable paths (default process.cwd())
    • saveRemote: enable/disable saving a local copy of remote sources (default true)
    • svgAsImage: convert <img inline src="*.svg" /> to <img> and not <svg> (default false)
    • swallowErrors: enable/disable suppression of errors (default false)
    $ npm install inline-source
    <!-- located at project/src/html/index.html -->
    <!DOCTYPE html>
        <!-- inline project/www/css/inlineStyle.css as <style> -->
        <link inline href="css/inlineStyle.css" />
        <!-- inline project/src/js/inlineScript.js as <script> -->
        <script inline src="../src/js/inlineScript.js"></script> 
        <!-- inline remote file as <script> -->
        <script inline src="http://js/inlineScript.js"></script> 
        <!-- inline project/www/images/inlineImage.png as base64 <img> -->
        <img inline src="images/inlineImage.png" />
        <!-- inline project/www/images/inlineImage.svg as <svg> -->
        <img inline src="images/inlineImage.svg" />
    const { inlineSource } = require('inline-source');
    const fs = require('fs');
    const path = require('path');
    const htmlpath = path.resolve('project/src/html/index.html');
    inlineSource(htmlpath, {
      compress: true,
      rootpath: path.resolve('www'),
      // Skip all css types and png formats
      ignore: ['css', 'png']
      .then((html) => {
        // Do something with html
      .catch((err) => {
        // Handle error

    ...or preferably using async/await:

    const { inlineSource } = require('inline-source');
    const fs = require('fs');
    const path = require('path');
    const htmlpath = path.resolve('project/src/html/index.html');
    let html;
    try {
      html = await inlineSource(htmlpath, {
        compress: true,
        rootpath: path.resolve('www'),
        // Skip all css types and png formats
        ignore: ['css', 'png']
      // Do something with html
    } catch (err) {
      // Handle error

    Custom Handlers

    Custom handlers are simple middleware-type functions that enable you to provide new, or override existing, inlining behaviour. All handlers have the following signature: (source, context) => Promise

    • source: the current source object to act upon

      • attributes: the parsed tag attributes object
      • compress: the compress flag (may be overriden at the tag level via props)
      • content: the processed fileContent string
      • extension: the file extension
      • fileContent: the loaded file content string
      • filepath: the fully qualified path string
      • format: the format string (jpg, gif, svg+xml, etc)
      • match: the matched html tag string, including closing tag if appropriate
      • props: the parsed namespaced attributes object (see props)
      • replace: the tag wrapped content string to replace match
      • tag: the tag string (script, link, etc)
      • type: the content type based on type mime-type attribute, or tag (js for application/javascript, css for text/css, etc)
    • context: the global context object storing all configuration options (attribute, compress, ignore, pretty, rootpath, swallowErrors, svgAsImage), in addtion to:

      • html: the html file's content string
      • htmlpath: the html file's path string
      • sources: the array of source objects

    Custom handlers are inserted before the defaults, enabling overriding of default behaviour:

    module.exports = function handler(source, context) {
      if (source.fileContent && !source.content && source.type == 'js') {
        source.content = "Hey! I'm overriding the file's content!";

    In general, default file content processing will be skipped if source.content is already set, and default wrapping of processed content will be skipped if source.replace is already set.

    Custom Pre Handlers

    Custom pre handlers are the same as custom handlers only they run before loading the file. All handlers have the following signature: (source, context) => Promise

    With custom Pre handlers you can make changes to the file name

    module.exports = function handler(source, context) {
      const { version } = require('../package.json');
      source.filepath = source.filepath.replace('.js', `_${version}.js`);


    Source props are a subset of attributes that are namespaced with the current global attribute ('inline' by default), and allow declaratively passing data or settings to handlers:

    module.exports = function handler(source, context) {
      if (source.fileContent && !source.content && source.type == 'js') {
        // The `inline-compress` attribute automatically overrides the global flag
        if (!source.compress) {
          // do something
        if ( == 'foo') {
          // foo content
      return Promise.resolve();


    npm i inline-source

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