es6-symbol

What is es6-symbol?

The es6-symbol npm package provides a polyfill for the Symbol type introduced in ECMAScript 6. It offers a way to create unique identifiers that can be used as property keys in objects without the risk of name clashes. This is particularly useful for creating private or special properties that should not interfere with other properties in the object.

What are es6-symbol's main functionalities?

Creating symbols

This feature allows the creation of symbols, which can be used as unique identifiers. The code sample demonstrates how to create a symbol using the es6-symbol package.

var symbol = require('es6-symbol');
var mySymbol = symbol('mySymbol');

Using symbols as property keys

Symbols can be used as property keys in objects. This code sample shows how to assign and access a property in an object using a symbol as the key.

var symbol = require('es6-symbol');
var mySymbol = symbol('mySymbol');
var obj = {};
obj[mySymbol] = 'value';
console.log(obj[mySymbol]); // 'value'

Well-known symbols

The package provides access to well-known symbols defined by the ECMAScript specification, such as Symbol.iterator. This code sample demonstrates how to access a well-known symbol.

var symbol = require('es6-symbol');
var iteratorSymbol = symbol.iterator;
console.log(typeof iteratorSymbol); // 'symbol'

Other packages similar to es6-symbol

core-js

core-js is a modular standard library for JavaScript, which includes polyfills for ECMAScript up to 2021. It covers a broader range of ECMAScript features compared to es6-symbol, including symbols. core-js is more comprehensive but might be overkill if you only need symbol functionality.

babel-runtime

babel-runtime provides a set of polyfills required for a full ES2015+ environment. It includes support for symbols among other features. Compared to es6-symbol, babel-runtime is part of the Babel ecosystem, making it a good choice if you're already using Babel for transpiling your JavaScript code.

README

es6-symbol

ECMAScript 6 Symbol polyfill

For more information about symbols see following links

• Symbols in ECMAScript 6 by Axel Rauschmayer
• MDN Documentation
• Specification

Limitations

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

Usage

If you'd like to use native version when it exists and fallback to ponyfill if it doesn't, use es6-symbol as following:

var Symbol = require("es6-symbol");

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

require("es6-symbol/implement");

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");

API

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 = iterator.next();
  while (!result.done) {
    console.log(result.value);
    result = iterator.next();
  }
}

Installation

NPM

In your project path:

$ npm install es6-symbol

Browser

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

Tests

$ npm test

Security contact information

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Changelog

3.1.4 (2024-03-01)

Maintenance Improvements