get-css-data

A micro-library for collecting stylesheet data from link and style nodes.

Features

Collects CSS data from <link> and <style> nodes
Collects static Node.textContent or live CSS Object Model (CSSOM) data
Returns CSS data as a concatenated string and a DOM-ordered array of strings
Allows document, iframe, and shadow DOM traversal
Handles @import rules
Handles absolute and relative URLs
Inspect, modify and/or filter CSS data from each node
Modify XHR object before each request
UMD and ES6 modules available
Compatible with modern and legacy browsers (IE9+)
Lightweight (less than 1.5k min+gzip) and dependency-free

Installation

NPM:

npm install get-css-data --save

// file.js
import getCssData from 'get-css-data';

getCssData({
  onComplete: function(cssText, cssArray, nodeArray) {
    // Do stuff...
  }
});

Git:

git clone https://github.com/jhildenbiddle/get-css-data.git

CDN (jsdelivr.com shown, also on unpkg.com):

<!-- ES5 (latest v2.x.x) -->
<script src="https://cdn.jsdelivr.net/npm/get-css-data@2"></script>
<script>
  getCssData({
    onComplete: function(cssText, cssArray, nodeArray) {
      // Do stuff...
    }
  });
</script>

<!-- ES6 module (latest v2.x.x) -->
<script type="module">
  import getCssData from 'https://cdn.jsdelivr.net/npm/get-css-data@2/dist/get-css-data.esm.min.js';

  getCssData({
    onComplete(cssText, cssArray, nodeArray) {
      // Do stuff...
    }
  });
</script>

Example

HTML:

<!-- file.html -->
<head>
  <link rel="stylesheet" href="style1.css">
  <style>
    @import "style2.css";
    p { color: blue; }
  </style>
</head>

CSS:

/* style1.css */
p { color: red; }

/* style2.css */
p { color: green; }

JavaScript (see Options for details)

getCssData({
  onComplete: function(cssText, cssArray, nodeArray) {
    console.log(cssText); // 1
    console.log(cssArray); // 2
    console.log(nodeArray); // 3
  }
});

// 1 => 'p { color: red; } p { color: green; } p { color: blue; }'
// 2 => ['p { color: red; }', 'p { color: green; } p { color: blue; }']
// 3 => [<linkElement>, <styleElement>]

Example

// Default values shown
getCssData({
  rootElement : document,
  include     : 'link[rel=stylesheet],style',
  exclude     : '',
  filter      : '',
  skipDisabled: true,
  useCSSOM    : false,
  onBeforeSend: function(xhr, node, url) {
    // ...
  },
  onSuccess: function(cssText, node, url) {
    // ...
  },
  onError: function(xhr, node, url) {
    // ...
  },
  onComplete: function(cssText, cssArray, nodeArray) {
    // ...
  }
});

options.rootElement

Type: object
Default: document

Root element to traverse for <link> and <style> nodes.

Examples

// Document
getCssData({
  rootElement: document // default
});

// Iframe (must be same domain with content loaded)
getCssData({
  rootElement: (myIframe.contentDocument || myIframe.contentWindow.document)
});

// Shadow DOM
getCssData({
  rootElement: myElement.shadowRoot
});

options.include

Type: string
Default: "link[rel=stylesheet],style"

CSS selector matching <link> and <style> nodes to collect data from. The default value includes all style and link nodes.

Example

getCssData({
  // Include only <link rel="stylesheet"> nodes
  // with an href that does not contains "bootstrap"
  include: 'link[rel=stylesheet]:not([href*=bootstrap])',
});

options.exclude

Type: string

CSS selector matching <link> and <style> nodes to exclude from those matched by options.include.

Example

getCssData({
  // Of matched `include` nodes, exclude any node
  // with an href that contains "bootstrap"
  exclude: '[href*=bootstrap]',
});

options.filter

Type: object

Regular expression used to filter node CSS data. Each block of CSS data is tested against the filter, and only matching data is processed.

Example

getCssData({
  // Test each block of CSS for the existence
  // of ".myclass". If found, process the CSS.
  // If not, ignore the CSS.
  filter: /\.myclass/,
});

options.skipDisabled

Type: boolean
Default: true

Determines if disabled stylesheets will be skipped while collecting CSS data.

Example

getCssData({
  skipDisabled: true // default
});

options.useCSSOM

Type: boolean
Default: false

Determines how CSS data will be collected from <style> nodes.

When false, static CSS data is collected by reading each node's textContent value. This method is fast, but the data collected will not reflect changes made using the deleteRule() or insertRule() methods. When true, live CSS data is collected by iterating over each node's CSSRuleList and concatenating all CSSRule.cssText values into a single string. This method is slower, but the data collected accurately reflects all changes made to the stylesheet.

Keep in mind that browsers often drop unrecognized selectors, properties, and values when parsing static CSS. For example, Chrome/Safari will drop declarations with Mozilla's -moz- prefix, while Firefox will drop declarations with Chrome/Safari's -webkit prefix . This means that data collected when this options is set to true will likely vary between browsers and differ from the static CSS collected when it is set to false.

Example

getCssData({
  useCSSOM: false // default
});

options.onBeforeSend

Type: function
Arguments:
1. xhr: The XHR object containing details of the request
2. node: The source node object reference
3. url: The source URL string (<link> href or @import url)

Callback before each XMLHttpRequest (XHR) is sent. Allows modifying the XML object by setting properties, calling methods, or adding event handlers.

Example

getCssData({
  onBeforeSend: function(xhr, node, url) {
    // Domain-specific XHR settings
    if (/some-domain.com/.test(url)) {
      xhr.withCredentials = true;
      xhr.setRequestHeader("foo", "1");
      xhr.setRequestHeader("bar", "2");
    }
  }
});

options.onSuccess

Type: function
Arguments:
1. cssText: A string of CSS text from node and url
2. node: The source node object reference
3. url: The source URL string (<link> href, @import url, or page url for <style> data)

Callback after CSS data has been collected from each node. Allows modifying the CSS data before it is added to the final output by returning any string value or skipping the CSS data by returning false or an empty string ("").

Note that the order in which <link> and @import CSS data is "successfully" collected (thereby triggering this callback) is not guaranteed as these requests are asynchronous. To access CSS data in DOM order, use the cssArray argument passed to the options.oncomplete callback.

Example

getCssData({
  onSuccess: function(cssText, node, url) {
    // Replace all instances of "color: red" with "color: blue"
    const newCssText = cssText.replace(/color:\s*red\s;/g, 'color: blue;');

    return newCssText;
  }
});

options.onError

Type: function
Arguments:
1. xhr: The XHR object containing details of the request
2. node: The source node object reference
3. url: The source URL string (<link> href or @import url)

Callback after <link> or @import request has failed or when xhr.responseText appears to be HTML instead of CSS.

Example

getCssData({
  onError: function(xhr, node, url) {
    console.log(xhr.status); // 1
    console.log(xhr.statusText); // 2
  }
});

// 1 => '404'
// 2 => 'Not Found'

options.onComplete

Type: function
Arguments:
1. cssText: A string of concatenated CSS text from all nodes in DOM order.
2. cssArray: An array of per-node CSS text in DOM order. The node containing each CSS text block is available at the same nodeArray index.
3. nodeArray: An array of processed <style> and <link> nodes in DOM order. The CSS text for each node is available at the same cssArray index.

Callback after CSS data has been collected from all nodes.

Example

getCssData({
  onComplete: function(cssText, cssArray, nodeArray) {
    // ...
  }
});

Sponsorship

A sponsorship is more than just a way to show appreciation for the open-source authors and projects we rely on; it can be the spark that ignites the next big idea, the inspiration to create something new, and the motivation to share so that others may benefit.

If you benefit from this project, please consider lending your support and encouraging future efforts by becoming a sponsor.

Thank you! 🙏🏻

Contact & Support

Follow 👨🏻‍💻 @jhildenbiddle on Twitter and GitHub for announcements
Create a 💬 GitHub issue for bug reports, feature requests, or questions
Add a ⭐️ star on GitHub and 🐦 tweet to promote the project
Become a 💖 sponsor to support the project and future efforts

License

This project is licensed under the MIT License. See the LICENSE for details.

Cheap and reliable Node.js hosting starts at $3/month, and $1/month static HTML hosting

jhildenbiddle / get-css-data

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Features

Installation

Example

Options

options.rootElement

options.include

options.exclude

options.filter

options.skipDisabled

options.useCSSOM

options.onBeforeSend

options.onSuccess

options.onError

options.onComplete

Sponsorship

Contact & Support

License