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");
const { getOnlyHandlerKey } = require("../util/handlerKeys");
const { propertyAccess } = require("../util/property");

/** @import Compilation from "../Compilation" */
/** @import { ReadOnlyRuntimeRequirements } from "../Module" */

class OnChunksLoadedRuntimeModule extends RuntimeModule {
	/**
	 * @param {ReadOnlyRuntimeRequirements} runtimeRequirements runtime requirements
	 */
	constructor(runtimeRequirements) {
		super("chunk loaded");
		/** @type {ReadOnlyRuntimeRequirements} */
		this.runtimeRequirements = runtimeRequirements;
	}

	/**
	 * The `[handlerMap, key]` pairs this module installs onto a chunk handler map
	 * such as `__webpack_require__.f`, or `null` where it cannot name them.
	 * @returns {[string, string][] | null} installed chunk handlers (do not mutate)
	 */
	getInstalledChunkHandlers() {
		// Reads a map rather than installing onto one, so reading its code back would
		// render it in a cycle.
		return RuntimeModule.NO_CHUNK_HANDLERS;
	}

	/**
	 * Generates runtime code for this runtime module.
	 * @returns {string | null} runtime code
	 */
	generate() {
		const compilation = /** @type {Compilation} */ (this.compilation);
		const { runtimeTemplate } = compilation;
		// Only a prefetch startup callback is queued behind a priority, so without one
		// the queue keeps insertion order and nothing has to hold the lowest seen.
		const withPriority = this.runtimeRequirements.has(
			RuntimeGlobals.hasChunkPriority
		);
		const only = getOnlyHandlerKey(this, RuntimeGlobals.onChunksLoaded);
		return Template.asString([
			`${runtimeTemplate.renderConst()} deferred = [];`,
			`${RuntimeGlobals.onChunksLoaded} = ${runtimeTemplate.basicFunction(
				`result, chunkIds, fn${withPriority ? ", priority" : ""}`,
				[
					"if(chunkIds) {",
					Template.indent(
						withPriority
							? [
									`${runtimeTemplate.assignOr("priority", "0")};`,
									"for(var i = deferred.length; i > 0 && deferred[i - 1][2] > priority; i--) deferred[i] = deferred[i - 1];",
									"deferred[i] = [chunkIds, fn, priority];",
									"return;"
								]
							: ["deferred.push([chunkIds, fn]);", "return;"]
					),
					"}",
					...(withPriority
						? [`${runtimeTemplate.renderLet()} notFulfilled = Infinity;`]
						: []),
					"for (var i = 0; i < deferred.length; i++) {",
					Template.indent([
						runtimeTemplate.destructureArray(
							withPriority
								? ["chunkIds", "fn", "priority"]
								: ["chunkIds", "fn"],
							"deferred[i]"
						),
						`${runtimeTemplate.renderLet()} fulfilled = true;`,
						"for (var j = 0; j < chunkIds.length; j++) {",
						Template.indent([
							// Parenthesized: `&` binds looser than `===`, so `priority & 1 === 0`
							// is `priority & false` and gates every priority, not just the odd ones.
							`if (${
								withPriority
									? "((priority & 1) === 0 || notFulfilled >= priority) && "
									: ""
							}${
								only === null
									? `Object.keys(${
											RuntimeGlobals.onChunksLoaded
										}).every(${runtimeTemplate.returningFunction(
											`${RuntimeGlobals.onChunksLoaded}[key](chunkIds[j])`,
											"key"
										)})`
									: `${RuntimeGlobals.onChunksLoaded}${propertyAccess([
											only
										])}(chunkIds[j])`
							}) {`,
							Template.indent(["chunkIds.splice(j--, 1);"]),
							"} else {",
							Template.indent(
								withPriority
									? [
											"fulfilled = false;",
											"if(priority < notFulfilled) notFulfilled = priority;"
										]
									: ["fulfilled = false;"]
							),
							"}"
						]),
						"}",
						"if(fulfilled) {",
						Template.indent([
							"deferred.splice(i--, 1)",
							`${runtimeTemplate.renderConst()} r = fn();`,
							"if (r !== undefined) result = r;"
						]),
						"}"
					]),
					"}",
					"return result;"
				]
			)};`
		]);
	}
}

module.exports = OnChunksLoadedRuntimeModule;