es6-map
Advanced tools
Package description
The es6-map npm package provides an implementation of the Map data structure as specified in ECMAScript 6 (ES6). This package is particularly useful for environments that do not fully support ES6 features, allowing developers to use Map functionalities such as maintaining key-value pairs where keys can be of any type and preserving the insertion order of keys.
Creating and initializing a Map
This feature allows the creation of a Map and initialization with key-value pairs. The 'get' method retrieves the value associated with a key.
const ES6Map = require('es6-map');
const map = new ES6Map([['key1', 'value1'], ['key2', 'value2']]);
console.log(map.get('key1')); // Outputs: 'value1'Checking existence of a key
This feature checks whether a specific key exists in the Map using the 'has' method.
const map = new ES6Map([['key1', 'value1']]);
console.log(map.has('key1')); // Outputs: true
console.log(map.has('key2')); // Outputs: falseIterating over Map entries
This feature demonstrates how to iterate over the entries of the Map, accessing both keys and values.
const map = new ES6Map([['key1', 'value1'], ['key2', 'value2']]);
for (let [key, value] of map) {
console.log(key + ': ' + value);
}The 'immutable' package provides persistent immutable data structures including Map, List, Set, etc. Unlike es6-map, which only offers a Map polyfill, 'immutable' offers a wide range of data structures and features like lazy operation chaining, deep persistence, and complex data nesting.
The 'collections' package offers data structures with performance in mind, including Map, Set, List, and others. It provides additional utilities compared to es6-map, such as sorted maps and sets, and specialized collections like Deque.
Readme
If you want to make sure your environment implements Map, do:
require('es6-map/implement');
If you'd like to use native version when it exists and fallback to polyfill if it doesn't, but without implementing Map on global scope, do:
var Map = require('es6-map');
If you strictly want to use polyfill even if native Map exists, do:
var Map = require('es6-map/polyfill');
$ npm install es6-map
To port it to Browser or any other (non CJS) environment, use your favorite CJS bundler. No favorite yet? Try: Browserify, Webmake or Webpack
Best is to refer to specification. Still if you want quick look, follow examples:
var Map = require('es6-map');
var x = {}, y = {}, map = new Map([['raz', 'one'], ['dwa', 'two'], [x, y]]);
map.size; // 3
map.get('raz'); // 'one'
map.get(x); // y
map.has('raz'); // true
map.has(x); // true
map.has('foo'); // false
map.set('trzy', 'three'); // map
map.size // 4
map.get('trzy'); // 'three'
map.has('trzy'); // true
map.has('dwa'); // true
map.delete('dwa'); // true
map.size; // 3
map.forEach(function (value, key) {
// { 'raz', 'one' }, { x, y }, { 'trzy', 'three' } iterated
});
// FF nightly only:
for (value of map) {
// ['raz', 'one'], [x, y], ['trzy', 'three'] iterated
}
var iterator = map.values();
iterator.next(); // { done: false, value: 'one' }
iterator.next(); // { done: false, value: y }
iterator.next(); // { done: false, value: 'three' }
iterator.next(); // { done: true, value: undefined }
map.clear(); // undefined
map.size; // 0
$ npm test
FAQs
ECMAScript6 Map polyfill
The npm package es6-map receives a total of 1,037,520 weekly downloads. As such, es6-map popularity was classified as popular.
We found that es6-map demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Security News
CISA launched a new project called Vulnrichment to enrich CVEs with details that help prioritize patching and mitigation efforts, as the NVD backlog of unenriched CVEs awaiting analysis surpasses 10,000.
Security News
Socket is joining forces with CISA and other industry leaders at the RSA Conference to sign the Secure by Design pledge, committing to uphold the highest security standards in our products.
Research
The Socket research team breaks down a sampling of malicious packages that download and execute files, among other suspicious behaviors, targeting the popular Discord platform.