webpack/lib/runtime/OnChunksLoadedRuntimeModule.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 RuntimeGlobals = require("../RuntimeGlobals");
const RuntimeModule = require("../RuntimeModule");
const Template = require("../Template");

/** @typedef {import("../Compilation")} Compilation */

class OnChunksLoadedRuntimeModule extends RuntimeModule {
	constructor() {
		super("chunk loaded");
	}

	/**
	 * @returns {string | null} runtime code
	 */
	generate() {
		const compilation = /** @type {Compilation} */ (this.compilation);
		const { runtimeTemplate } = compilation;
		return Template.asString([
			"var deferred = [];",
			`${RuntimeGlobals.onChunksLoaded} = ${runtimeTemplate.basicFunction(
				"result, chunkIds, fn, priority",
				[
					"if(chunkIds) {",
					Template.indent([
						"priority = priority || 0;",
						"for(var i = deferred.length; i > 0 && deferred[i - 1][2] > priority; i--) deferred[i] = deferred[i - 1];",
						"deferred[i] = [chunkIds, fn, priority];",
						"return;"
					]),
					"}",
					"var notFulfilled = Infinity;",
					"for (var i = 0; i < deferred.length; i++) {",
					Template.indent([
						runtimeTemplate.destructureArray(
							["chunkIds", "fn", "priority"],
							"deferred[i]"
						),
						"var fulfilled = true;",
						"for (var j = 0; j < chunkIds.length; j++) {",
						Template.indent([
							`if ((priority & 1 === 0 || notFulfilled >= priority) && Object.keys(${
								RuntimeGlobals.onChunksLoaded
							}).every(${runtimeTemplate.returningFunction(
								`${RuntimeGlobals.onChunksLoaded}[key](chunkIds[j])`,
								"key"
							)})) {`,
							Template.indent(["chunkIds.splice(j--, 1);"]),
							"} else {",
							Template.indent([
								"fulfilled = false;",
								"if(priority < notFulfilled) notFulfilled = priority;"
							]),
							"}"
						]),
						"}",
						"if(fulfilled) {",
						Template.indent([
							"deferred.splice(i--, 1)",
							"var r = fn();",
							"if (r !== undefined) result = r;"
						]),
						"}"
					]),
					"}",
					"return result;"
				]
			)};`
		]);
	}
}

module.exports = OnChunksLoadedRuntimeModule;