map.prototype.getorinsert

An ESnext spec-compliant Map.prototype.getOrInsert shim/polyfill/replacement that works as far down as ES3.

This package implements the es-shim API v3 interface. It works in an ES3-supported environment and complies with the proposed spec.

Getting started

npm install --save map.prototype.getorinsert

Usage/Examples

var getOrInsert = require('map.prototype.getorinsert');
var assert = require('assert');

var map = new Map();
var key = {};
var value = {};

assert.equal(map.has(key), false);
assert.equal(getOrInsert(map, key, value), value);
assert.equal(map.has(key), true);

var getPolyfill = require('map.prototype.getorinsert/polyfill');
var shim = require('map.prototype.getorinsert/shim');
var assert = require('assert');
/* when Map.prototype.getOrInsert is not present */
delete Map.prototype.getOrInsert;
var shimmed = shim();

assert.equal(shimmed, getPolyfill());

var map = new Map();
var key = {};
var value = {};

assert.equal(map.has(key), false);
assert.equal(map.getOrInsert(key, value), value);
assert.equal(map.has(key), true);

var shim = require('map.prototype.getorinsert/shim');
var assert = require('assert');
/* when Map.prototype.getOrInsert is present */
var shimmed = shim();

assert.equal(shimmed, Map.prototype.getOrInsert);

var map = new Map();
var key = {};
var value = {};

assert.equal(map.has(key), false);
assert.equal(map.getOrInsert(key, value), value);
assert.equal(map.has(key), true);

Tests

Simply clone the repo, npm install, and run npm test