webpack/lib/dependencies/importOptionsCheck.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 Alexander Akait @alexander-akait
*/

"use strict";

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

/** @import RuntimeTemplate from "../RuntimeTemplate" */

/**
 * Wraps an import so its arguments evaluate in source order and the options are
 * checked, rejecting rather than throwing. The last parameter holds them.
 * @param {RuntimeTemplate} runtimeTemplate the runtime template
 * @param {string[]} parameters parameter names, the options one last
 * @param {string} content the import expression to return once the check passes
 * @returns {string} the wrapping function
 */
const importOptionsCheck = (runtimeTemplate, parameters, content) => {
	const options = parameters[parameters.length - 1];
	return runtimeTemplate.basicFunction(parameters.join(", "), [
		"try {",
		Template.indent([
			`if (${options} !== undefined) {`,
			Template.indent([
				`if ((typeof ${options} !== "object" && typeof ${options} !== "function") || ${options} === null) throw new TypeError("The second argument to import() must be an object");`,
				`var a = ${options}["with"];`,
				"if (a !== undefined) {",
				Template.indent([
					'if ((typeof a !== "object" && typeof a !== "function") || a === null) throw new TypeError("The \'with\' option must be an object");',
					"for (var k = Object.keys(a), i = 0; i < k.length; i++) {",
					Template.indent([
						'if (typeof a[k[i]] !== "string") throw new TypeError("Import attribute values must be strings");'
					]),
					"}"
				]),
				"}"
			]),
			"}"
		]),
		"} catch (e) { return Promise.reject(e); }",
		`return ${content};`
	]);
};

module.exports = importOptionsCheck;