47 lines
1.4 KiB
JavaScript
47 lines
1.4 KiB
JavaScript
'use strict';
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// modified from https://github.com/es-shims/es6-shim
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var objectKeys = require('object-keys');
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var hasSymbols = require('has-symbols/shams')();
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var callBound = require('call-bind/callBound');
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var toObject = Object;
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var $push = callBound('Array.prototype.push');
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var $propIsEnumerable = callBound('Object.prototype.propertyIsEnumerable');
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var originalGetSymbols = hasSymbols ? Object.getOwnPropertySymbols : null;
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// eslint-disable-next-line no-unused-vars
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module.exports = function assign(target, source1) {
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if (target == null) { throw new TypeError('target must be an object'); }
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var to = toObject(target); // step 1
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if (arguments.length === 1) {
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return to; // step 2
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}
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for (var s = 1; s < arguments.length; ++s) {
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var from = toObject(arguments[s]); // step 3.a.i
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// step 3.a.ii:
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var keys = objectKeys(from);
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var getSymbols = hasSymbols && (Object.getOwnPropertySymbols || originalGetSymbols);
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if (getSymbols) {
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var syms = getSymbols(from);
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for (var j = 0; j < syms.length; ++j) {
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var key = syms[j];
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if ($propIsEnumerable(from, key)) {
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$push(keys, key);
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}
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}
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}
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// step 3.a.iii:
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for (var i = 0; i < keys.length; ++i) {
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var nextKey = keys[i];
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if ($propIsEnumerable(from, nextKey)) { // step 3.a.iii.2
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var propValue = from[nextKey]; // step 3.a.iii.2.a
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to[nextKey] = propValue; // step 3.a.iii.2.b
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}
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}
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}
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return to; // step 4
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};
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