Neglected Pulse Machine


    0.8.0 • Public • Published


    Array extras for regular expressions.

    Also provides optional String and RegExp prototype extensions.

    No more writing the implementation-detail-leaking, non-semantic, and otherwise ugly:

    let matches;
    while ((matches = regex.exec(str)) !== null) {
      // Do something
      if (condition) {

    While all of the array extras could be useful, some, might be the most general purpose as it (as with every) allows short-circuiting (breaking).

    The following is equivalent to that above (though with matches as local):

    RegExtras(regex).some(str, (matches) => {
      // Do something
      if (condition) {
        return true;
      return false;

    And if the condition is at the end of the loop, just this:

    RegExtras(regex).some(str, (matches) => {
      // Do something
      return condition;



    const RegExtras = require('regextras');

    Modern browsers:

    import {RegExtras} from './node_modules/regextras/dist/index-es.js';

    Older browsers:

    <script src="regextras/dist/index-umd.js"></script>

    The prototype versions must be required or included separately.

    If you need the generator methods, you should also add the following:

    <script src="regextras/dist/index-generators-umd.js"></script>



    new RegExtras(regex, flags, newLastIndex)


    const piglatinArray = RegExtras(/\w*w?ay/).reduce('ouyay areway illysay', function (arr, i, word) {
      if (word.endsWith('way')) { arr.push(word.replace(/way$/, '')); } else { arr.push(word.slice(-3, -2) + word.slice(0, -3)); }
      return arr;
    }, []);

    All arguments but the first are optional, and the first argument can be expressed as a string.

    The new keywords is not required.

    Instance methods

    These methods (and their callbacks) behave like the array extra to which they correspond with exceptions detailed below.

    • forEach(str, callback, thisObject) - Unlike the other extras, this method returns the RegExtras object (to enable chaining).

    • some(str, callback, thisObject)

    • every(str, callback, thisObject)

    • map(str, callback, thisObject)

    • filter(str, callback, thisObject)

    • reduce(str, cb, prev, thisObj) - Unlike the array extras, allows a fourth argument to set an alternative value for this within the callback.

    • reduceRight(str, cb, prev, thisObj) - Unlike the array extras, allows a fourth argument to set an alternative value for this within the callback.

    • find(str, cb, thisObj)

    • findIndex(str, cb, thisObj)

    Also adds the following methods:

    • findExec(str, cb, thisObj) - Operates like find() except that it returns the exec result array (with index and input as well as numeric properties as returned by RegExp.prototype.exec).

    • filterExec(str, cb, thisObj) - Operates like filter() except that the resulting array will contain the full exec results.

    If you are using the Node version (or if, for the browser, you add the index-generators.js file and you are only supporting modern browsers), one can use the following generator methods:

    • values(str) - Returns an iterator with the array of matches (for each RegExp.prototype.exec result)

    • keys(str) - Returns an iterator with 0-based indexes (from RegExp.prototype.exec result)

    • entries(str) - Returns an iterator with an array containing the key and the array of matches (for each RegExp.prototype.exec result)

    Class methods

    • mixinRegex(regex, newFlags='', newLastIndex=regex.lastIndex) - Makes a copy of a regular expression.


    All callbacks follow the signature:

    cb(n1, n2..., i, n0);

    ...except for the reduce and reduceRight callbacks which follow:

    cb(prev, n1, n2..., i, n0);

    Prototype versions

    String and RegExp versions of the above methods are also available.

    The RegExp prototype version acts in the same way as RegExtra just without the need for a separate constructor call.

    The String prototype version differs in that instead of the first argument being a string, it is the regular expression.


    1. Could add Array accessor methods like slice(), with an additional supplied regular expression to gather the exec results into an array.

    2. Utilize nodeunit browser testing (and add mixinRegex tests)

      1. Convert nodeunit tests to ES6 modules running through babel-register?; streamline as sole set of tests, reconciling test with tests folder
    3. Add generators for prototype versions


    npm i regextras

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