webpack/lib/async-modules/AwaitDependenciesInitFragment.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
	Author Tobias Koppers @sokra
*/

"use strict";

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

/** @typedef {import("webpack-sources").Source} Source */
/** @typedef {import("../Generator").GenerateContext} GenerateContext */

/**
 * @extends {InitFragment<GenerateContext>}
 */
class AwaitDependenciesInitFragment extends InitFragment {
	/**
	 * @param {Set<string>} promises the promises that should be awaited
	 */
	constructor(promises) {
		super(
			undefined,
			InitFragment.STAGE_ASYNC_DEPENDENCIES,
			0,
			"await-dependencies"
		);
		this.promises = promises;
	}

	/**
	 * @param {AwaitDependenciesInitFragment} other other AwaitDependenciesInitFragment
	 * @returns {AwaitDependenciesInitFragment} AwaitDependenciesInitFragment
	 */
	merge(other) {
		const promises = new Set(other.promises);
		for (const p of this.promises) {
			promises.add(p);
		}
		return new AwaitDependenciesInitFragment(promises);
	}

	/**
	 * @param {GenerateContext} context context
	 * @returns {string | Source | undefined} the source code that will be included as initialization code
	 */
	getContent({ runtimeRequirements }) {
		runtimeRequirements.add(RuntimeGlobals.module);
		const promises = this.promises;
		if (promises.size === 0) {
			return "";
		}
		if (promises.size === 1) {
			for (const p of promises) {
				return Template.asString([
					`var __webpack_async_dependencies__ = __webpack_handle_async_dependencies__([${p}]);`,
					`${p} = (__webpack_async_dependencies__.then ? (await __webpack_async_dependencies__)() : __webpack_async_dependencies__)[0];`,
					""
				]);
			}
		}
		const sepPromises = Array.from(promises).join(", ");
		// TODO check if destructuring is supported
		return Template.asString([
			`var __webpack_async_dependencies__ = __webpack_handle_async_dependencies__([${sepPromises}]);`,
			`([${sepPromises}] = __webpack_async_dependencies__.then ? (await __webpack_async_dependencies__)() : __webpack_async_dependencies__);`,
			""
		]);
	}
}

module.exports = AwaitDependenciesInitFragment;