Element.classList

/*
 * classList.js: Cross-browser full element.classList implementation.
 * 1.1.20170427
 *
 * By Eli Grey, http://eligrey.com
 * License: Dedicated to the public domain.
 *   See https://github.com/eligrey/classList.js/blob/master/LICENSE.md
 */

/*global self, document, DOMException */

/*! @source http://purl.eligrey.com/github/classList.js/blob/master/classList.js */

if ("document" in self) {

	// Full polyfill for browsers with no classList support
	// Including IE < Edge missing SVGElement.classList
	if (!("classList" in document.createElement("_"))
		|| document.createElementNS && !("classList" in document.createElementNS("http://www.w3.org/2000/svg", "g"))) {

		(function (view) {

			"use strict";

			if (!('Element' in view)) return;

			var
				classListProp = "classList"
				, protoProp = "prototype"
				, elemCtrProto = view.Element[protoProp]
				, objCtr = Object
				, strTrim = String[protoProp].trim || function () {
					return this.replace(/^\s+|\s+$/g, "");
				}
				, arrIndexOf = Array[protoProp].indexOf || function (item) {
					var
						i = 0
						, len = this.length
						;
					for (; i < len; i++) {
						if (i in this && this[i] === item) {
							return i;
						}
					}
					return -1;
				}
				// Vendors: please allow content code to instantiate DOMExceptions
				, DOMEx = function (type, message) {
					this.name = type;
					this.code = DOMException[type];
					this.message = message;
				}
				, checkTokenAndGetIndex = function (classList, token) {
					if (token === "") {
						throw new DOMEx(
							"SYNTAX_ERR"
							, "An invalid or illegal string was specified"
						);
					}
					if (/\s/.test(token)) {
						throw new DOMEx(
							"INVALID_CHARACTER_ERR"
							, "String contains an invalid character"
						);
					}
					return arrIndexOf.call(classList, token);
				}
				, ClassList = function (elem) {
					var
						trimmedClasses = strTrim.call(elem.getAttribute("class") || "")
						, classes = trimmedClasses ? trimmedClasses.split(/\s+/) : []
						, i = 0
						, len = classes.length
						;
					for (; i < len; i++) {
						this.push(classes[i]);
					}
					this._updateClassName = function () {
						elem.setAttribute("class", this.toString());
					};
				}
				, classListProto = ClassList[protoProp] = []
				, classListGetter = function () {
					return new ClassList(this);
				}
				;
			// Most DOMException implementations don't allow calling DOMException's toString()
			// on non-DOMExceptions. Error's toString() is sufficient here.
			DOMEx[protoProp] = Error[protoProp];
			classListProto.item = function (i) {
				return this[i] || null;
			};
			classListProto.contains = function (token) {
				token += "";
				return checkTokenAndGetIndex(this, token) !== -1;
			};
			classListProto.add = function () {
				var
					tokens = arguments
					, i = 0
					, l = tokens.length
					, token
					, updated = false
					;
				do {
					token = tokens[i] + "";
					if (checkTokenAndGetIndex(this, token) === -1) {
						this.push(token);
						updated = true;
					}
				}
				while (++i < l);

				if (updated) {
					this._updateClassName();
				}
			};
			classListProto.remove = function () {
				var
					tokens = arguments
					, i = 0
					, l = tokens.length
					, token
					, updated = false
					, index
					;
				do {
					token = tokens[i] + "";
					index = checkTokenAndGetIndex(this, token);
					while (index !== -1) {
						this.splice(index, 1);
						updated = true;
						index = checkTokenAndGetIndex(this, token);
					}
				}
				while (++i < l);

				if (updated) {
					this._updateClassName();
				}
			};
			classListProto.toggle = function (token, force) {
				token += "";

				var
					result = this.contains(token)
					, method = result ?
						force !== true && "remove"
						:
						force !== false && "add"
					;

				if (method) {
					this[method](token);
				}

				if (force === true || force === false) {
					return force;
				} else {
					return !result;
				}
			};
			classListProto.toString = function () {
				return this.join(" ");
			};

			if (objCtr.defineProperty) {
				var classListPropDesc = {
					get: classListGetter
					, enumerable: true
					, configurable: true
				};
				try {
					objCtr.defineProperty(elemCtrProto, classListProp, classListPropDesc);
				} catch (ex) { // IE 8 doesn't support enumerable:true
					// adding undefined to fight this issue https://github.com/eligrey/classList.js/issues/36
					// modernie IE8-MSW7 machine has IE8 8.0.6001.18702 and is affected
					if (ex.number === undefined || ex.number === -0x7FF5EC54) {
						classListPropDesc.enumerable = false;
						objCtr.defineProperty(elemCtrProto, classListProp, classListPropDesc);
					}
				}
			} else if (objCtr[protoProp].__defineGetter__) {
				elemCtrProto.__defineGetter__(classListProp, classListGetter);
			}

		}(self));

	}

	// There is full or partial native classList support, so just check if we need
	// to normalize the add/remove and toggle APIs.

	(function () {
		"use strict";

		var testElement = document.createElement("_");

		testElement.classList.add("c1", "c2");

		// Polyfill for IE 10/11 and Firefox <26, where classList.add and
		// classList.remove exist but support only one argument at a time.
		if (!testElement.classList.contains("c2")) {
			var createMethod = function (method) {
				var original = DOMTokenList.prototype[method];

				DOMTokenList.prototype[method] = function (token) {
					var i, len = arguments.length;

					for (i = 0; i < len; i++) {
						token = arguments[i];
						original.call(this, token);
					}
				};
			};
			createMethod('add');
			createMethod('remove');
		}

		testElement.classList.toggle("c3", false);

		// Polyfill for IE 10 and Firefox <24, where classList.toggle does not
		// support the second argument.
		if (testElement.classList.contains("c3")) {
			var _toggle = DOMTokenList.prototype.toggle;

			DOMTokenList.prototype.toggle = function (token, force) {
				if (1 in arguments && !this.contains(token) === !force) {
					return force;
				} else {
					return _toggle.call(this, token);
				}
			};

		}

		testElement = null;
	}());

}