react-native/Libraries/polyfills/Object.es6.js

71 lines
2.3 KiB
JavaScript

/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
* @providesModule Object.es6
* @polyfill
* @nolint
*/
/* eslint-disable strict */
// WARNING: This is an optimized version that fails on hasOwnProperty checks
// and non objects. It's not spec-compliant. It's a perf optimization.
// This is only needed for iOS 8 and current Android JSC.
Object.assign = function(target, sources) {
if (__DEV__) {
if (target == null) {
throw new TypeError('Object.assign target cannot be null or undefined');
}
if (typeof target !== 'object' && typeof target !== 'function') {
throw new TypeError(
'In this environment the target of assign MUST be an object. ' +
'This error is a performance optimization and not spec compliant.'
);
}
}
for (var nextIndex = 1; nextIndex < arguments.length; nextIndex++) {
var nextSource = arguments[nextIndex];
if (nextSource == null) {
continue;
}
if (__DEV__) {
if (typeof nextSource !== 'object' &&
typeof nextSource !== 'function') {
throw new TypeError(
'In this environment the sources for assign MUST be an object. ' +
'This error is a performance optimization and not spec compliant.'
);
}
}
// We don't currently support accessors nor proxies. Therefore this
// copy cannot throw. If we ever supported this then we must handle
// exceptions and side-effects.
for (var key in nextSource) {
if (__DEV__) {
var hasOwnProperty = Object.prototype.hasOwnProperty;
if (!hasOwnProperty.call(nextSource, key)) {
throw new TypeError(
'One of the sources for assign has an enumerable key on the ' +
'prototype chain. Are you trying to assign a prototype property? ' +
'We don\'t allow it, as this is an edge case that we do not support. ' +
'This error is a performance optimization and not spec compliant.'
);
}
}
target[key] = nextSource[key];
}
}
return target;
};