57 lines
1.7 KiB
JavaScript
57 lines
1.7 KiB
JavaScript
/**
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @flow
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* @format
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*/
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'use strict';
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const defineLazyObjectProperty = require('./defineLazyObjectProperty');
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/**
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* Sets an object's property. If a property with the same name exists, this will
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* replace it but maintain its descriptor configuration. The property will be
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* replaced with a lazy getter.
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*
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* In DEV mode the original property value will be preserved as `original[PropertyName]`
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* so that, if necessary, it can be restored. For example, if you want to route
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* network requests through DevTools (to trace them):
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*
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* global.XMLHttpRequest = global.originalXMLHttpRequest;
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*
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* @see https://github.com/facebook/react-native/issues/934
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*/
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function polyfillObjectProperty<T>(
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object: Object,
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name: string,
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getValue: () => T,
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): void {
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const descriptor = Object.getOwnPropertyDescriptor(object, name);
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if (__DEV__ && descriptor) {
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const backupName = `original${name[0].toUpperCase()}${name.substr(1)}`;
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Object.defineProperty(object, backupName, descriptor);
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}
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const {enumerable, writable, configurable} = descriptor || {};
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if (descriptor && !configurable) {
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console.error('Failed to set polyfill. ' + name + ' is not configurable.');
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return;
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}
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defineLazyObjectProperty(object, name, {
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get: getValue,
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enumerable: enumerable !== false,
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writable: writable !== false,
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});
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}
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function polyfillGlobal<T>(name: string, getValue: () => T): void {
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polyfillObjectProperty(global, name, getValue);
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}
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module.exports = {polyfillObjectProperty, polyfillGlobal};
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