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6d8d948ad0
The dynamically compiled ESM import helper is now cached to prevent the need to recompile the helper function everytime a load ESM helper call is made. This helper is currently used to workaround dynamic import limitations with the TypeScript compilation output. Once the build process is updated, it will no longer be required.
34 lines
1.2 KiB
TypeScript
34 lines
1.2 KiB
TypeScript
/**
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* @license
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* Copyright Google LLC All Rights Reserved.
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*
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* Use of this source code is governed by an MIT-style license that can be
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* found in the LICENSE file at https://angular.io/license
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*/
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/**
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* Lazily compiled dynamic import loader function.
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*/
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let load: (<T>(modulePath: string | URL) => Promise<T>) | undefined;
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/**
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* This uses a dynamic import to load a module which may be ESM.
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* CommonJS code can load ESM code via a dynamic import. Unfortunately, TypeScript
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* will currently, unconditionally downlevel dynamic import into a require call.
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* require calls cannot load ESM code and will result in a runtime error. To workaround
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* this, a Function constructor is used to prevent TypeScript from changing the dynamic import.
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* Once TypeScript provides support for keeping the dynamic import this workaround can
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* be dropped.
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*
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* @param modulePath The path of the module to load.
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* @returns A Promise that resolves to the dynamically imported module.
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*/
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export function loadEsmModule<T>(modulePath: string | URL): Promise<T> {
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load ??= new Function('modulePath', `return import(modulePath);`) as Exclude<
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typeof load,
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undefined
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>;
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return load(modulePath);
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}
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