webpack/lib/prefetch/ChunkPrefetchFunctionRuntimeModule.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
*/

"use strict";

const RuntimeModule = require("../RuntimeModule");
const Template = require("../Template");

/** @import Compilation from "../Compilation" */

class ChunkPrefetchFunctionRuntimeModule extends RuntimeModule {
	/**
	 * Returns true, if the runtime module should get it's own scope.
	 * When false, `generate()` must emit complete statements ending with `;`
	 * so a following runtime IIFE is not parsed as a call (ASI).
	 * @returns {boolean} true, if the runtime module should get it's own scope
	 */
	shouldIsolate() {
		return false;
	}

	/**
	 * @param {"prefetch" | "preload"} type "prefetch" or "preload" chunk type function
	 * @param {string | null} runtimeFunction the runtime function name, or `null` where nothing fans out over the handlers
	 * @param {string} runtimeHandlers the runtime handlers
	 */
	constructor(type, runtimeFunction, runtimeHandlers) {
		super(`chunk ${type} function`);
		/** @type {string | null} */
		this.runtimeFunction = runtimeFunction;
		/** @type {string} */
		this.runtimeHandlers = runtimeHandlers;
	}

	/**
	 * Generates runtime code for this runtime module.
	 * @returns {string | null} runtime code
	 */
	generate() {
		const { runtimeFunction, runtimeHandlers } = this;
		const compilation = /** @type {Compilation} */ (this.compilation);
		const { runtimeTemplate } = compilation;
		return Template.asString([
			`${runtimeHandlers} = {};`,
			...(runtimeFunction === null
				? []
				: [
						`${runtimeFunction} = ${runtimeTemplate.basicFunction("chunkId", [
							// map is shorter than forEach
							`Object.keys(${runtimeHandlers}).map(${runtimeTemplate.basicFunction(
								"key",
								`${runtimeHandlers}[key](chunkId);`
							)});`
						])};`
					])
		]);
	}
}

module.exports = ChunkPrefetchFunctionRuntimeModule;