prariehill / es6-iterator

Iterator abstraction as specified in ECMAScript6

es6-iterator

ECMAScript 6 Iterator interface

Installation

$ npm install es6-iterator

To port it to Browser or any other (non CJS) environment, use your favorite CJS bundler. No favorite yet? Try: Browserify, Webmake or Webpack

API

Constructors

Iterator(list) (es6-iterator)

Abstract Iterator interface. Meant for extensions and not to be used on its own.

Accepts any list object (technically object with numeric length property).

Mind it doesn't iterate strings properly, for that use dedicated StringIterator

var Iterator = require('es6-iterator')
var iterator = new Iterator([1, 2, 3]);

iterator.next(); // { value: 1, done: false }
iterator.next(); // { value: 2, done: false }
iterator.next(); // { value: 3, done: false }
iterator.next(); // { value: undefined, done: true }

ArrayIterator(arrayLike[, kind]) (es6-iterator/array)

Dedicated for arrays and array-likes. Supports three iteration kinds:

• value (default) - Iterates values
• key - Iterates indexes
• key+value - Iterates keys and indexes, each iteration value is in [key, value] form.

var ArrayIterator = require('es6-iterator/array')
var iterator = new ArrayIterator([1, 2, 3], 'key+value');

iterator.next(); // { value: [0, 1], done: false }
iterator.next(); // { value: [1, 2], done: false }
iterator.next(); // { value: [2, 3], done: false }
iterator.next(); // { value: undefined, done: true }

May also be used for arguments objects:

(function () {
  var iterator = new ArrayIterator(arguments);

  iterator.next(); // { value: 1, done: false }
  iterator.next(); // { value: 2, done: false }
  iterator.next(); // { value: 3, done: false }
  iterator.next(); // { value: undefined, done: true }
}(1, 2, 3));

StringIterator(str) (es6-iterator/string)

Assures proper iteration over unicode symbols.
See: http://mathiasbynens.be/notes/javascript-unicode

var StringIterator = require('es6-iterator/string');
var iterator = new StringIterator('f🙈o🙉o🙊');

iterator.next(); // { value: 'f', done: false }
iterator.next(); // { value: '🙈', done: false }
iterator.next(); // { value: 'o', done: false }
iterator.next(); // { value: '🙉', done: false }
iterator.next(); // { value: 'o', done: false }
iterator.next(); // { value: '🙊', done: false }
iterator.next(); // { value: undefined, done: true }

Function utilities

forOf(iterable, callback[, thisArg]) (es6-iterator/for-of)

Polyfill for ECMAScript 6 for...of statement.

var forOf = require('es6-iterator/for-of');
var result = [];

forOf('🙈🙉🙊', function (monkey) { result.push(monkey); });
console.log(result); // ['🙈', '🙉', '🙊'];

Optionally you can break iteration at any point:

var result = [];

forOf([1,2,3,4]', function (val, doBreak) {
  result.push(monkey);
  if (val >= 3) doBreak();
});
console.log(result); // [1, 2, 3];

get(obj) (es6-iterator/get)

Return iterator for any iterable object.

var getIterator = require('es6-iterator/get');
var iterator = get([1,2,3]);

iterator.next(); // { value: 1, done: false }
iterator.next(); // { value: 2, done: false }
iterator.next(); // { value: 3, done: false }
iterator.next(); // { value: undefined, done: true }

isIterable(obj) (es6-iterator/is-iterable)

Whether obj is iterable

var isIterable = require('es6-iterator/is-iterable');

isIterable(null); // false
isIterable(true); // false
isIterable('str'); // true
isIterable(['a', 'r', 'r']); // true
isIterable(new ArrayIterator([])); // true

validIterable(obj) (es6-iterator/valid-iterable)

If obj is an iterable it is returned. Otherwise TypeError is thrown.

Method extensions

iterator.chain(iterator1[, …iteratorn]) (es6-iterator/#/chain)

Chain multiple iterators into one.

Tests

$ npm test