32 lines
1.0 KiB
JavaScript
32 lines
1.0 KiB
JavaScript
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/**
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* Copyright (c) Meta Platforms, Inc. and 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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/**
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* @return whether or not a @param {function} f is provided natively by calling
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* `toString` and check if the result includes `[native code]` in it.
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*
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* Note that a polyfill can technically fake this behavior but few does it.
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* Therefore, this is usually good enough for our purpose.
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*/
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function isNativeFunction(f: Function): boolean {
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return typeof f === 'function' && f.toString().indexOf('[native code]') > -1;
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}
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/**
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* @return whether or not the constructor of @param {object} o is an native
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* function named with @param {string} expectedName.
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*/
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function hasNativeConstructor(o: Object, expectedName: string): boolean {
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const con = Object.getPrototypeOf(o).constructor;
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return con.name === expectedName && isNativeFunction(con);
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}
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module.exports = {isNativeFunction, hasNativeConstructor};
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