webpack/lib/util/propertyAccess.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support 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 SAFE_IDENTIFIER = /^[_a-zA-Z$][_a-zA-Z$0-9]*$/;
const RESERVED_IDENTIFIER = new Set([
	"break",
	"case",
	"catch",
	"class",
	"const",
	"continue",
	"debugger",
	"default",
	"delete",
	"do",
	"else",
	"export",
	"extends",
	"finally",
	"for",
	"function",
	"if",
	"import",
	"in",
	"instanceof",
	"new",
	"return",
	"super",
	"switch",
	"this",
	"throw",
	"try",
	"typeof",
	"var",
	"void",
	"while",
	"with",
	"enum",
	// strict mode
	"implements",
	"interface",
	"let",
	"package",
	"private",
	"protected",
	"public",
	"static",
	"yield",
	"yield",
	// module code
	"await",
	// skip future reserved keywords defined under ES1 till ES3
	// additional
	"null",
	"true",
	"false"
]);

const propertyAccess = (properties, start = 0) => {
	let str = "";
	for (let i = start; i < properties.length; i++) {
		const p = properties[i];
		if (`${+p}` === p) {
			str += `[${p}]`;
		} else if (SAFE_IDENTIFIER.test(p) && !RESERVED_IDENTIFIER.has(p)) {
			str += `.${p}`;
		} else {
			str += `[${JSON.stringify(p)}]`;
		}
	}
	return str;
};

module.exports = propertyAccess;