source: frontend/node_modules/webpack/lib/runtime/StartupChunkDependenciesRuntimeModule.js

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Tobias Koppers @sokra
*/

"use strict";

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

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

class StartupChunkDependenciesRuntimeModule extends RuntimeModule {
        /**
         * @param {boolean} asyncChunkLoading use async chunk loading
         */
        constructor(asyncChunkLoading) {
                super("startup chunk dependencies", RuntimeModule.STAGE_TRIGGER);
                /** @type {boolean} */
                this.asyncChunkLoading = asyncChunkLoading;
        }

        /**
         * Generates runtime code for this runtime module.
         * @returns {string | null} runtime code
         */
        generate() {
                const chunkGraph = /** @type {ChunkGraph} */ (this.chunkGraph);
                const chunk = /** @type {Chunk} */ (this.chunk);
                const chunkIds = [
                        ...chunkGraph.getChunkEntryDependentChunksIterable(chunk)
                ].map((chunk) => chunk.id);
                const compilation = /** @type {Compilation} */ (this.compilation);
                const { runtimeTemplate } = compilation;
                return Template.asString([
                        `var next = ${RuntimeGlobals.startup};`,
                        `${RuntimeGlobals.startup} = ${runtimeTemplate.basicFunction(
                                "",
                                !this.asyncChunkLoading
                                        ? [
                                                        ...chunkIds.map(
                                                                (id) => `${RuntimeGlobals.ensureChunk}(${JSON.stringify(id)});`
                                                        ),
                                                        "return next();"
                                                ]
                                        : chunkIds.length === 1
                                                ? `return ${RuntimeGlobals.ensureChunk}(${JSON.stringify(
                                                                chunkIds[0]
                                                        )}).then(next);`
                                                : chunkIds.length > 2
                                                        ? [
                                                                        // using map is shorter for 3 or more chunks
                                                                        `return Promise.all(${JSON.stringify(chunkIds)}.map(${
                                                                                RuntimeGlobals.ensureChunk
                                                                        }, ${RuntimeGlobals.require})).then(next);`
                                                                ]
                                                        : [
                                                                        // calling ensureChunk directly is shorter for 0 - 2 chunks
                                                                        "return Promise.all([",
                                                                        Template.indent(
                                                                                chunkIds
                                                                                        .map(
                                                                                                (id) =>
                                                                                                        `${RuntimeGlobals.ensureChunk}(${JSON.stringify(id)})`
                                                                                        )
                                                                                        .join(",\n")
                                                                        ),
                                                                        "]).then(next);"
                                                                ]
                        )};`
                ]);
        }
}

module.exports = StartupChunkDependenciesRuntimeModule;