source: frontend/node_modules/webpack/lib/prefetch/ChunkPreloadTriggerRuntimeModule.js

/*
        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 */
/** @typedef {import("../Chunk").ChunkChildIdsByOrdersMap} ChunkChildIdsByOrdersMap */

class ChunkPreloadTriggerRuntimeModule extends RuntimeModule {
        /**
         * @param {ChunkChildIdsByOrdersMap} chunkMap map from chunk to chunks
         */
        constructor(chunkMap) {
                super("chunk preload trigger", RuntimeModule.STAGE_TRIGGER);
                /** @type {ChunkChildIdsByOrdersMap} */
                this.chunkMap = chunkMap;
        }

        /**
         * Generates runtime code for this runtime module.
         * @returns {string | null} runtime code
         */
        generate() {
                const { chunkMap } = this;
                const compilation = /** @type {Compilation} */ (this.compilation);
                const { runtimeTemplate } = compilation;
                const body = [
                        "var chunks = chunkToChildrenMap[chunkId];",
                        `Array.isArray(chunks) && chunks.map(${RuntimeGlobals.preloadChunk});`
                ];
                return Template.asString([
                        Template.asString([
                                `var chunkToChildrenMap = ${JSON.stringify(chunkMap, null, "\t")};`,
                                `${
                                        RuntimeGlobals.ensureChunkHandlers
                                }.preload = ${runtimeTemplate.basicFunction("chunkId", body)};`
                        ])
                ]);
        }
}

module.exports = ChunkPreloadTriggerRuntimeModule;