dedupe.js

/*!
  Copyright (c) 2017 Jed Watson.
  Licensed under the MIT License (MIT), see
  http://jedwatson.github.io/classnames
*/
/* global define */

(function () {
	'use strict';

	var classNames = (function () {
		// don't inherit from Object so we can skip hasOwnProperty check later
		// http://stackoverflow.com/questions/15518328/creating-js-object-with-object-createnull#answer-21079232
		function StorageObject() {}
		StorageObject.prototype = Object.create(null);

		function _parseArray (resultSet, array) {
			var length = array.length;

			for (var i = 0; i < length; ++i) {
				_parse(resultSet, array[i]);
			}
		}

		var hasOwn = {}.hasOwnProperty;

		function _parseNumber (resultSet, num) {
			resultSet[num] = true;
		}

		function _parseObject (resultSet, object) {
			for (var k in object) {
				if (hasOwn.call(object, k)) {
					// set value to false instead of deleting it to avoid changing object structure
					// https://www.smashingmagazine.com/2012/11/writing-fast-memory-efficient-javascript/#de-referencing-misconceptions
					resultSet[k] = !!object[k];
				}
			}
		}

		var SPACE = /\s+/;
		function _parseString (resultSet, str) {
			var array = str.split(SPACE);
			var length = array.length;

			for (var i = 0; i < length; ++i) {
				resultSet[array[i]] = true;
			}
		}

		function _parse (resultSet, arg) {
			if (!arg) return;
			var argType = typeof arg;

			// 'foo bar'
			if (argType === 'string') {
				_parseString(resultSet, arg);

			// ['foo', 'bar', ...]
			} else if (Array.isArray(arg)) {
				_parseArray(resultSet, arg);

			// { 'foo': true, ... }
			} else if (argType === 'object') {
				_parseObject(resultSet, arg);

			// '130'
			} else if (argType === 'number') {
				_parseNumber(resultSet, arg);
			}
		}

		function _classNames () {
			// don't leak arguments
			// https://github.com/petkaantonov/bluebird/wiki/Optimization-killers#32-leaking-arguments
			var len = arguments.length;
			var args = Array(len);
			for (var i = 0; i < len; i++) {
				args[i] = arguments[i];
			}

			var classSet = new StorageObject();
			_parseArray(classSet, args);

			var list = [];

			for (var k in classSet) {
				if (classSet[k]) {
					list.push(k)
				}
			}

			return list.join(' ');
		}

		return _classNames;
	})();

	if (typeof module !== 'undefined' && module.exports) {
		module.exports = classNames;
	} else if (typeof define === 'function' && typeof define.amd === 'object' && define.amd) {
		// register as 'classnames', consistent with npm package name
		define('classnames', [], function () {
			return classNames;
		});
	} else {
		window.classNames = classNames;
	}
}());