polyfill-service/polyfills/_DOMTokenList/polyfill.js

A polyfill combinator

var _DOMTokenList = (function (global) {

	function tokenize(token) {
		if (/^-?[_a-zA-Z]+[_a-zA-Z0-9-]*$/.test(token)) {
			return String(token);
		} else {
			throw new Error('InvalidCharacterError: DOM Exception 5');
		}
	}

	function toObject(self) {
		for (var index = -1, object = {}, element; element = self[++index];) {
			object[element] = true;
		}

		return object;
	}

	function fromObject(self, object) {
		var array = [], token;

		for (token in object) {
			if (object[token]) {
				array.push(token);
			}
		}

		[].splice.apply(self, [0, self.length].concat(array));
	}

	var DTL = function() {};

	DTL.prototype = {
		constructor: DTL,
		item: function item(index) {
			return this[parseFloat(index)] || null;
		},
		length: Array.prototype.length,
		toString: function toString() {
			return [].join.call(this, ' ');
		},

		add: function add() {
			for (var object = toObject(this), index = 0, token; index in arguments; ++index) {
				token = tokenize(arguments[index]);

				object[token] = true;
			}

			fromObject(this, object);
		},
		contains: function contains(token) {
			return token in toObject(this);
		},
		remove: function remove() {
			for (var object = toObject(this), index = 0, token; index in arguments; ++index) {
				token = tokenize(arguments[index]);

				object[token] = false;
			}

			fromObject(this, object);
		},
		toggle: function toggle(token) {
			var
			object = toObject(this),
			contains = 1 in arguments ? !arguments[1] : tokenize(token) in object;

			object[token] = !contains;

			fromObject(this, object);

			return !contains;
		}
	};

	return DTL;

})(this);