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linkify-it

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Links recognition library with FULL unicode support. Focused on high quality link patterns detection in plain text.

Demo

Why it's awesome:

  • Full unicode support, with astral characters!
  • International domains support.
  • Allows rules extension & custom normalizers.

Install

npm install linkify-it --save

Browserification is also supported.

Usage examples

Example 1
var linkify = require('linkify-it')();

// Reload full tlds list & add unofficial `.onion` domain.
linkify
  .tlds(require('tlds'))          // Reload with full tlds list
  .tlds('onion', true)            // Add unofficial `.onion` domain
  .add('git:', 'http:')           // Add `git:` protocol as "alias"
  .add('ftp:', null)              // Disable `ftp:` protocol
  .set({ fuzzyIP: true });        // Enable IPs in fuzzy links (without schema)

console.log(linkify.test('Site github.com!'));  // true

console.log(linkify.match('Site github.com!')); // [ {
                                                //   schema: "",
                                                //   index: 5,
                                                //   lastIndex: 15,
                                                //   raw: "github.com",
                                                //   text: "github.com",
                                                //   url: "http://github.com",
                                                // } ]
Example 2. Add twitter mentions handler
linkify.add('@', {
  validate: function (text, pos, self) {
    var tail = text.slice(pos);

    if (!self.re.twitter) {
      self.re.twitter =  new RegExp(
        '^([a-zA-Z0-9_]){1,15}(?!_)(?=$|' + self.re.src_ZPCc + ')'
      );
    }
    if (self.re.twitter.test(tail)) {
      // Linkifier allows punctuation chars before prefix,
      // but we additionally disable `@` ("@@mention" is invalid)
      if (pos >= 2 && tail[pos - 2] === '@') {
        return false;
      }
      return tail.match(self.re.twitter)[0].length;
    }
    return 0;
  },
  normalize: function (match) {
    match.url = 'https://twitter.com/' + match.url.replace(/^@/, '');
  }
});

API

API documentation

new LinkifyIt(schemas, options)

Creates new linkifier instance with optional additional schemas. Can be called without new keyword for convenience.

By default understands:

  • http(s)://... , ftp://..., mailto:... & //... links
  • "fuzzy" links and emails (google.com, foo@bar.com).

schemas is an object, where each key/value describes protocol/rule:

  • key - link prefix (usually, protocol name with : at the end, skype: for example). linkify-it makes sure that prefix is not preceded with alphanumeric char.
  • value - rule to check tail after link prefix
    • String - just alias to existing rule
    • Object
      • validate - either a RegExp (start with ^, and don't include the link prefix itself), or a validator function which, given arguments text, pos, and self, returns the length of a match in text starting at index pos. pos is the index right after the link prefix. self can be used to access the linkify object to cache data.
      • normalize - optional function to normalize text & url of matched result (for example, for twitter mentions).

options:

  • fuzzyLink - recognize URL-s without http(s):// head. Default true.
  • fuzzyIP - allow IPs in fuzzy links above. Can conflict with some texts like version numbers. Default false.
  • fuzzyEmail - recognize emails without mailto: prefix. Default true.
  • --- - set true to terminate link with --- (if it's considered as long dash).

.test(text)

Searches linkifiable pattern and returns true on success or false on fail.

.pretest(text)

Quick check if link MAY BE can exist. Can be used to optimize more expensive .test() calls. Return false if link can not be found, true - if .test() call needed to know exactly.

.testSchemaAt(text, name, offset)

Similar to .test() but checks only specific protocol tail exactly at given position. Returns length of found pattern (0 on fail).

.match(text)

Returns Array of found link matches or null if nothing found.

Each match has:

  • schema - link schema, can be empty for fuzzy links, or // for protocol-neutral links.
  • index - offset of matched text
  • lastIndex - index of next char after mathch end
  • raw - matched text
  • text - normalized text
  • url - link, generated from matched text

.tlds(list[, keepOld])

Load (or merge) new tlds list. Those are needed for fuzzy links (without schema) to avoid false positives. By default:

  • 2-letter root zones are ok.
  • biz|com|edu|gov|net|org|pro|web|xxx|aero|asia|coop|info|museum|name|shop|рф are ok.
  • encoded (xn--...) root zones are ok.

If that's not enough, you can reload defaults with more detailed zones list.

.add(key, value)

Add a new schema to the schemas object. As described in the constructor definition, key is a link prefix (skype:, for example), and value is a String to alias to another schema, or an Object with validate and optionally normalize definitions. To disable an existing rule, use .add(key, null).

.set(options)

Override default options. Missed properties will not be changed.

License

MIT

LinkifyIt

Constructor

LinkifyIt.new

    • new LinkifyIt(schemas, options)
    • schemas
      • Object
    • Optional. Additional schemas to validate (prefix/validator)

    • options
      • Object
    • { fuzzyLink|fuzzyEmail|fuzzyIP: true|false }

Creates new linkifier instance with optional additional schemas. Can be called without new keyword for convenience.

By default understands:

  • http(s)://... , ftp://..., mailto:... & //... links
  • "fuzzy" links and emails (example.com, foo@bar.com).

schemas is an object, where each key/value describes protocol/rule:

  • key - link prefix (usually, protocol name with : at the end, skype: for example). linkify-it makes shure that prefix is not preceeded with alphanumeric char and symbols. Only whitespaces and punctuation allowed.
  • value - rule to check tail after link prefix
    • String - just alias to existing rule
    • Object
      • validate - validator function (should return matched length on success), or RegExp.
      • normalize - optional function to normalize text & url of matched result (for example, for @twitter mentions).

options:

  • fuzzyLink - recognige URL-s without http(s): prefix. Default true.
  • fuzzyIP - allow IPs in fuzzy links above. Can conflict with some texts like version numbers. Default false.
  • fuzzyEmail - recognize emails without mailto: prefix.

LinkifyIt#add

chainable
    • LinkifyIt#add(schema, definition)
    • schema
      • String
    • rule name (fixed pattern prefix)

    • definition
      • String
      • RegExp
      • Object
    • schema definition

Add new rule definition. See constructor description for details.

LinkifyIt#match

    • LinkifyIt#match(text)
      • Array
      • null

Returns array of found link descriptions or null on fail. We strongly recommend to use LinkifyIt#test first, for best speed.

Result match description
  • schema - link schema, can be empty for fuzzy links, or // for protocol-neutral links.
  • index - offset of matched text
  • lastIndex - index of next char after mathch end
  • raw - matched text
  • text - normalized text
  • url - link, generated from matched text

LinkifyIt#normalize

    • LinkifyIt#normalize(match)

Default normalizer (if schema does not define it's own).

LinkifyIt#onCompile

    • LinkifyIt#onCompile()

Override to modify basic RegExp-s.

LinkifyIt#pretest

    • LinkifyIt#pretest(text)
      • Boolean

Very quick check, that can give false positives. Returns true if link MAY BE can exists. Can be used for speed optimization, when you need to check that link NOT exists.

LinkifyIt#set

chainable
    • LinkifyIt#set(options)
    • options
      • Object
    • { fuzzyLink|fuzzyEmail|fuzzyIP: true|false }

Set recognition options for links without schema.

LinkifyIt#test

    • LinkifyIt#test(text)
      • Boolean

Searches linkifiable pattern and returns true on success or false on fail.

LinkifyIt#testSchemaAt

    • LinkifyIt#testSchemaAt(text, name, position)
      • Number
    • text
      • String
    • text to scan

    • name
      • String
    • rule (schema) name

    • position
      • Number
    • text offset to check from

Similar to LinkifyIt#test but checks only specific protocol tail exactly at given position. Returns length of found pattern (0 on fail).

LinkifyIt#tlds

chainable
    • LinkifyIt#tlds(list[, keepOld])
      • this
    • list
      • Array
    • list of tlds

    • keepOld
      • Boolean
    • merge with current list if true (false by default)

Load (or merge) new tlds list. Those are user for fuzzy links (without prefix) to avoid false positives. By default this algorythm used:

  • hostname with any 2-letter root zones are ok.
  • biz|com|edu|gov|net|org|pro|web|xxx|aero|asia|coop|info|museum|name|shop|рф are ok.
  • encoded (xn--...) root zones are ok.

If list is replaced, then exact match for 2-chars root zones will be checked.

Match

Description

Match result. Single element of array, returned by LinkifyIt#match

Match#index

    • Match#index
      • Number

First position of matched string.

Match#lastIndex

    • Match#lastIndex
      • Number

Next position after matched string.

Match#raw

    • Match#raw
      • String

Matched string.

Match#schema

    • Match#schema
      • String

Prefix (protocol) for matched string.

Match#text

    • Match#text
      • String

Notmalized text of matched string.

Match#url

    • Match#url
      • String

Normalized url of matched string.