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Name	Size	Permission	Action
auto.js	36 B	-rw-r--r--
hasSymbols.js	1.58 KB	-rw-r--r--
implementation.js	1.3 KB	-rw-r--r--
index.js	532 B	-rw-r--r--
package.json	1.93 KB	-rw-r--r--
polyfill.js	1.27 KB	-rw-r--r--
shim.js	305 B	-rw-r--r--

Code Editor : polyfill.js

'use strict';

var implementation = require('./implementation');

var lacksProperEnumerationOrder = function () {
	if (!Object.assign) {
		return false;
	}
	/*
	 * v8, specifically in node 4.x, has a bug with incorrect property enumeration order
	 * note: this does not detect the bug unless there's 20 characters
	 */
	var str = 'abcdefghijklmnopqrst';
	var letters = str.split('');
	var map = {};
	for (var i = 0; i < letters.length; ++i) {
		map[letters[i]] = letters[i];
	}
	var obj = Object.assign({}, map);
	var actual = '';
	for (var k in obj) {
		actual += k;
	}
	return str !== actual;
};

var assignHasPendingExceptions = function () {
	if (!Object.assign || !Object.preventExtensions) {
		return false;
	}
	/*
	 * Firefox 37 still has "pending exception" logic in its Object.assign implementation,
	 * which is 72% slower than our shim, and Firefox 40's native implementation.
	 */
	var thrower = Object.preventExtensions({ 1: 2 });
	try {
		Object.assign(thrower, 'xy');
	} catch (e) {
		return thrower[1] === 'y';
	}
	return false;
};

module.exports = function getPolyfill() {
	if (!Object.assign) {
		return implementation;
	}
	if (lacksProperEnumerationOrder()) {
		return implementation;
	}
	if (assignHasPendingExceptions()) {
		return implementation;
	}
	return Object.assign;
};