63 lines
2.6 KiB
JavaScript
63 lines
2.6 KiB
JavaScript
// Copyright (c) Microsoft Corporation. All rights reserved.
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// Licensed under the MIT License.
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import { ObjCreate, strShimFunction, strShimObject, strShimPrototype, strShimUndefined } from "./Constants";
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var _cachedGlobal = null;
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/**
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* Returns the current global scope object, for a normal web page this will be the current
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* window, for a Web Worker this will be current worker global scope via "self". The internal
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* implementation returns the first available instance object in the following order
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* - globalThis (New standard)
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* - self (Will return the current window instance for supported browsers)
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* - window (fallback for older browser implementations)
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* - global (NodeJS standard)
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* - <null> (When all else fails)
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* While the return type is a Window for the normal case, not all environments will support all
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* of the properties or functions.
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*/
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export function getGlobal(useCached) {
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if (useCached === void 0) { useCached = true; }
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var result = useCached === false ? null : _cachedGlobal;
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if (!result) {
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if (typeof globalThis !== strShimUndefined) {
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result = globalThis;
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}
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if (!result && typeof self !== strShimUndefined) {
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result = self;
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}
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if (!result && typeof window !== strShimUndefined) {
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result = window;
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}
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if (!result && typeof global !== strShimUndefined) {
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result = global;
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}
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_cachedGlobal = result;
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}
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return result;
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}
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export function throwTypeError(message) {
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throw new TypeError(message);
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}
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/**
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* Creates an object that has the specified prototype, and that optionally contains specified properties. This helper exists to avoid adding a polyfil
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* for older browsers that do not define Object.create eg. ES3 only, IE8 just in case any page checks for presence/absence of the prototype implementation.
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* Note: For consistency this will not use the Object.create implementation if it exists as this would cause a testing requirement to test with and without the implementations
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* @param obj Object to use as a prototype. May be null
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*/
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export function objCreateFn(obj) {
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var func = ObjCreate;
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// Use build in Object.create
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if (func) {
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// Use Object create method if it exists
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return func(obj);
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}
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if (obj == null) {
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return {};
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}
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var type = typeof obj;
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if (type !== strShimObject && type !== strShimFunction) {
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throwTypeError("Object prototype may only be an Object:" + obj);
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}
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function tmpFunc() { }
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tmpFunc[strShimPrototype] = obj;
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return new tmpFunc();
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}
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