mirror of
https://github.com/zhigang1992/react-native.git
synced 2026-04-14 23:18:06 +08:00
ad0fe15e2e
Summary:
React Native bundler (aka Metro Bundler) was splitted from the main codebase some time ago (now it lives [[https://github.com/facebook/metro-bundler|here]]). To make it more agnostic, polyfills will be moved out from it, so people who doesn't need them does not include them. However, RN will still need them, so the first step is to copy them back to RN so that we can provide them to Metro Bundler later.
We also include a way of passing the list of polyfills to include, as an `Array<string>`. The field is called `polyfills`, and defaults to the traditional list that is currently included in the package manager [see here](be1843cddc/packages/metro-bundler/src/defaults.js (L27-L37)).
In future commits, `metro-bundler` will be able to manage the `polyfills` array passed to it, and use it, instead of the pre-defined ones.
Reviewed By: davidaurelio
Differential Revision: D5381614
fbshipit-source-id: 749d536b781843ecb3067803e44398cd6df941f1
69 lines
2.2 KiB
JavaScript
69 lines
2.2 KiB
JavaScript
/**
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* Copyright (c) 2015-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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* @polyfill
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*/
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/* eslint-disable strict */
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// WARNING: This is an optimized version that fails on hasOwnProperty checks
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// and non objects. It's not spec-compliant. It's a perf optimization.
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// This is only needed for iOS 8 and current Android JSC.
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Object.assign = function(target, sources) {
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if (__DEV__) {
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if (target == null) {
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throw new TypeError('Object.assign target cannot be null or undefined');
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}
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if (typeof target !== 'object' && typeof target !== 'function') {
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throw new TypeError(
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'In this environment the target of assign MUST be an object.' +
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'This error is a performance optimization and not spec compliant.'
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);
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}
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}
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for (var nextIndex = 1; nextIndex < arguments.length; nextIndex++) {
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var nextSource = arguments[nextIndex];
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if (nextSource == null) {
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continue;
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}
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if (__DEV__) {
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if (typeof nextSource !== 'object' &&
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typeof nextSource !== 'function') {
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throw new TypeError(
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'In this environment the sources for assign MUST be an object.' +
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'This error is a performance optimization and not spec compliant.'
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);
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}
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}
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// We don't currently support accessors nor proxies. Therefore this
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// copy cannot throw. If we ever supported this then we must handle
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// exceptions and side-effects.
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for (var key in nextSource) {
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if (__DEV__) {
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var hasOwnProperty = Object.prototype.hasOwnProperty;
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if (!hasOwnProperty.call(nextSource, key)) {
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throw new TypeError(
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'One of the sources for assign has an enumerable key on the ' +
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'prototype chain. Are you trying to assign a prototype property? ' +
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'We don\'t allow it, as this is an edge case that we do not support. ' +
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'This error is a performance optimization and not spec compliant.'
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);
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}
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}
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target[key] = nextSource[key];
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}
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}
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return target;
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};
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