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authorruki <waruqi@gmail.com>2018-11-08 00:38:48 +0800
committerruki <waruqi@gmail.com>2018-11-07 21:53:09 +0800
commit26105034da4fcce7ac883c899d781f016559310d (patch)
treec459a5dc4e3aa0972d9919033ece511ce76dd129 /node_modules/object.assign/polyfill.js
parent2c77f00f1a7ecb6c8192f9c16d3b2001b254a107 (diff)
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-rw-r--r--node_modules/object.assign/polyfill.js51
1 files changed, 51 insertions, 0 deletions
diff --git a/node_modules/object.assign/polyfill.js b/node_modules/object.assign/polyfill.js
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+'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;
+};