A JavaScript library for linkification stuff. Used by linkify-plus-plus.

This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require


Linkify Plus Plus Core

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A JavaScript library for linkification stuff. Used by linkify-plus-plus.



This module exports 2 classes.

  • UrlMatcher - a URL matcher which can match almost all types of links from a string.
  • Linkifier - to linkify an element.


  • Tested on Firefox >= 56.
  • Support HTML/XHTML pages.


npm install linkify-plus-plus-core
const {UrlMatcher, Linkifier} = require("linkify-plus-plus-core");
// or use the matcher only
const {UrlMatcher} = require("linkify-plus-plus-core/lib/url-matcher")

There is also a browserified standalone build in dist folder, which can be included in your html directly.

<script src="path/to/linkify-plus-plus-core.js"></script>
// access the module with "linkifyPlusPlusCore" global
const {UrlMatcher, Linkifier} = linkifyPlusPlusCore;
</script> CDN:


// create a matcher
const matcher = new UrlMatcher();

for (const link of matcher.match(text)) {
    // matcher.match() returns a generator, yielding an object for each match result
    console.log(link.start, link.end, link.text, link.url);
// Linkifier needs a matcher to work
const linkifier = new Linkifier(document.body, {matcher: matcher});

// Linkifier will walk through the DOM tree, match url against all text nodes, and replace them with anchor element.
linkifier.on("complete", elapse => {
    console.log(`finished in ${elapse}ms`);
linkifier.on("error", err => {
    console.log("failed with error:", err);

// It is suggested to use `linkify()` function which wraps Linkifier to a promise.
linkify(document.body, {matcher}).then(onComplete, onError);

API references

This module exports:

  • UrlMatcher - a class to find link from string
  • Linkifier - a class to linkify elements
  • linkify - a function wrapping Linkifier. Return a promise.
  • INVALID_TAGS - a table of uppercase tag name, which are invalid ancestors for <a> element.


const urlMatcher = new UrlMatcher({
  fuzzyIp: Boolean,
  mail: Boolean,
  ignoreMustache: Boolean,
  unicode: Boolean,
  customRules: Array<String>,
  standalone: Boolean,
  boundaryLeft: String,
  boundaryRight: String

All options are optional:

  • fuzzyIp - match 4 digits IP, which often looks like version numbers. Default: true
  • mail - match email. Default: true
  • ignoreMustache - ignore links inside mustache "{{", "}}". This is useful to work with other template library like Vue.js. Default: false
  • unicode - match unicode character. Default: false
  • customRules - a list of regex pattern (in string). E.g. ["file:///\\S+", "magnet:\\?\\S+"]. Default: []
  • standalone - the link must be surrounded by whitespace. Default: false
  • boundaryLeft - has no effect without the standalone option. Allow some characters to be placed between whitespace and link. Some common characters are {[("'. Default: ""
  • boundaryRight - has no effect without the standalone option. Allow some characters to be placed between whitespace and link. Some common characters are '")]},.;?!. Default: ""


for (const matchResult of urlMatcher.match(text: String)) {

Match the text and return a generator which yields matched results.

matchResult object:

matchResult: {
  start: Integer,
  end: Integer,
  text: String,
  url: String,
  custom: Boolean,
  protocol: String,
  auth: String,
  domain: String,
  port: String,
  path: String
  • start - the start position of the url.
  • end - the end position of the url.
  • text - matched text.
  • url - the url of the link. .url doesn't always equal .text, that .text might lack of the protocol but .url is always a full URL.
  • custom - indicate if the result is matched by custom 4rules.

Other properties i.e. .protocol, .auth, .domain, .port, and .path are different parts of the URL.


const linkifier = new Linkifier([root: Element, ] options: Object);

This class extends event-lite.

  • root - the element that is going to be linkified.

options object:

options: {
  matcher: UrlMatcher,
  validator?: Function,
  newTab?: Boolean,
  noOpener?: Boolean,
  root?: Element,
  embedImage?: Boolean,
  maxRunTime?: Number,
  timeout?: Number,
  recursive?: Boolean
  • matcher - A UrlMatcher, required.

In fact, any object having a .match method which accepts a string and returns an iterable of matched result should work.

The match result must have .start, .end, .text, and .url properties described above.

  • validator - A function recieving an element and returning a boolean to decide if the element should be linkified. Note that the elements in INVALID_TAGS are already filtered out before the validator.
  • newTab - add target="_blank" to the link. Default: true
  • noOpener - add rel="noopener" to the link. Default: true
  • root - if you didn't supply the position argument root argument to the constructor, this value is used.
  • embedImage - create <img> for the link if the URL looks like an image. Default: true
  • maxRunTime - in milliseconds. The linkify process is split into small chunks to avoid blocking. This is the max execution time of each chunk. Default: 100
  • timeout - in milliseconds. If linkification have processed over this value, an error is raised. Note that any heavy work between each chunks are counted as in timeout too. Default: 10000
  • recursive - if true, linkify the entire node tree. Otherwise, only text nodes under root are linkified. Default: true



Start linkification. The linkifier would walk through the DOM tree, collect text nodes and <wbr> tags, match URLs with matcher, and convert them into links.



Abort linkification.

linkifier events

Linkifier emits following events, which could be listened with .on:

  • complete - emitted when the linkification completed. Listener arguments:

    • elapse: Number - time in milliseconds that the linkifier took to complete.
  • error - emitted when the linkification failed. Listener arguments:

    • error: Error - The error.
  • link - emitted when a link is created. You can alter the style, or implement your link builder to replace the default one. Listener arguments:

    • An object containing following properties:
    • result: Object - the result object yielded by UrlMatcher.match()
    • range: Range - the text range that the linkifier is working on. Do not change the range unless you know what you are doing.
    • link: AnchorElement - the link element.
    • content: DocumentFragment - the text (including <wbr> tags) extracted from matched text range, which is usually used as the content of the link.


async linkify([root: Element, ] options: Object)

A convenient function to setup/start a linkifier. See Linkifier for the arguments. Additionally, if the options object has some keys starting with on, the function treats them as event listeners. You can register event listeners like:

  onlink: ({link}) => {...}

Other notes


In the very old days, the script is based on Linkify Plus. Although it has been rewritten multiple times, the original license can be found here.

TLD list is grabbed from

TLD count is grabbed from


  • 0.6.1 (Feb 16, 2024)

    • Fix: options is undefined error.
  • 0.6.0 (Feb 14, 2024)

    • Add: recursive option in Linkifier.
    • Update TLDs.
  • 0.5.3 (Mar 10, 2021)

    • Fix: allow domains starting with digits.
  • 0.5.2 (Feb 12, 2021)

    • Fix: infinite loop bug.
  • 0.5.1 (Feb 11, 2021)

    • Update TLDs.
    • Change: match custom rules first.
    • Fix: handle invalid domains in a better way.
  • 0.5.0 (Oct 29, 2020)

    • Update TLDs.
    • Add: mail option.
    • Add: embed webp and apng.
    • Change: the matcher will only verify TLD if the protocol is http(s) or mailto.
  • 0.4.1 (Jun 17, 2019)

    • Update TLDs.
  • 0.4.0 (Feb 17, 2019)

    • Breaking: drop Firefox < 56.
    • Breaking: drop babel.
    • Breaking: INVALID_TAGS is now in lower-case.
    • Add: support XHTML pages.
    • Update TLDs.
  • 0.3.0 (Aug 23, 2017)

    • Drop: Linkifier.prototype.linkify. Now Linkifier uses event pattern.
    • Add linkify function.
    • Update TLDs.
  • 0.2.0 (Mar 4, 2017)

    • Use standalone build instead of require.
    • Fix: blocking bug with large element without matching urls.
  • 0.1.0 (Feb 23, 2017)

    • First release