Files
react-native/Libraries/Utilities/PolyfillFunctions.js
T
Rubén Norte 4409642811 Migrate large amount of modules to flow strict and strict-local
Summary:
| Group | Before | After | Change |
| Untyped | 50 | 49 | -1 |
| flow | 197 | 155 | -42 |
| flow strict-local | 226 | 185 | -41 |
| flow strict | 33 | 117 | +84

Changelog: [Changed] Improved Flow typing of multiple modules (with migrations to `flow strict` and `flow strict-local`

Reviewed By: motiz88

Differential Revision: D22549140

fbshipit-source-id: ed29415332cfce15b244ee4dea9e13d035543175
2020-07-22 09:46:16 -07:00

57 lines
1.7 KiB
JavaScript

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