source: frontend/node_modules/webpack/lib/prefetch/ChunkPrefetchStartupRuntimeModule.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("../Chunk")} Chunk */
/** @typedef {import("../Chunk").ChunkChildOfTypeInOrder} ChunkChildOfTypeInOrder */
/** @typedef {import("../Compilation")} Compilation */

class ChunkPrefetchStartupRuntimeModule extends RuntimeModule {
        /**
         * @param {ChunkChildOfTypeInOrder[]} startupChunks chunk ids to trigger when chunks are loaded
         */
        constructor(startupChunks) {
                super("startup prefetch", RuntimeModule.STAGE_TRIGGER);
                /** @type {ChunkChildOfTypeInOrder[]} */
                this.startupChunks = startupChunks;
        }

        /**
         * Generates runtime code for this runtime module.
         * @returns {string | null} runtime code
         */
        generate() {
                const { startupChunks } = this;
                const compilation = /** @type {Compilation} */ (this.compilation);
                const chunk = /** @type {Chunk} */ (this.chunk);
                const { runtimeTemplate } = compilation;
                return Template.asString(
                        startupChunks.map(
                                ({ onChunks, chunks }) =>
                                        `${RuntimeGlobals.onChunksLoaded}(0, ${JSON.stringify(
                                                // This need to include itself to delay execution after this chunk has been fully loaded
                                                onChunks.filter((c) => c === chunk).map((c) => c.id)
                                        )}, ${runtimeTemplate.basicFunction(
                                                "",
                                                chunks.size < 3
                                                        ? Array.from(
                                                                        chunks,
                                                                        (c) =>
                                                                                `${RuntimeGlobals.prefetchChunk}(${JSON.stringify(c.id)});`
                                                                )
                                                        : `${JSON.stringify(Array.from(chunks, (c) => c.id))}.map(${
                                                                        RuntimeGlobals.prefetchChunk
                                                                });`
                                        )}, 5);`
                        )
                );
        }
}

module.exports = ChunkPrefetchStartupRuntimeModule;