ECMAScript 6 Symbol polyfill


For more information about symbols see following links

Underneath it uses real string property names which can easily be retrieved, however accidental collision with other property names is unlikely.

It’s safest to use es6-symbol as a ponyfill – a polyfill which doesn’t touch global objects:

var Symbol = require('es6-symbol');

If you want to make sure your environment implements Symbol globally, do:


If you strictly want to use polyfill even if native Symbol exists (hard to find a good reason for that), do:

var Symbol = require('es6-symbol/polyfill');

Best is to refer to specification. Still if you want quick look, follow examples:

var Symbol = require('es6-symbol');
var symbol = Symbol('My custom symbol');
var x = {};
x[symbol] = 'foo';
console.log(x[symbol]); 'foo'
// Detect iterable: 
var iterator, result;
if (possiblyIterable[Symbol.iterator]) {
  iterator = possiblyIterable[Symbol.iterator]();
  result =;
  while(!result.done) {
    result =;

In your project path:

$ npm install es6-symbol

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


$ npm test