DOMTokenList Polyfill

/**
 * DOMTokenList polyfill
 * https://github.com/Alhadis/DOMTokenList-Polyfill
 *
 * Tested with IE8 & IE9.
 * Naturally, this script does absolutely nothing if the browser already supports DOMTokenList (which is virtually every modern browser, it's just versions of Explorer between 8-9 that can't hack it).
 */

/** COMPRESSED: */
window.DOMTokenList||function(){var t="defineProperty"in Object||"__defineGetter__"in Object.prototype||null,e=function(e,n,i,r){Object.defineProperty?Object.defineProperty(e,n,{configurable:!1===t?!0:!!r,get:i}):e.__defineGetter__(n,i)};if(t)try{e({},"support")}catch(n){t=!1}var i=function(t,n){var i,r=[],l={},s=0,o=0,a=function(){if(s>=o)for(;s>o;++o)(function(t){e(this,t,function(){return c.call(this),r[t]},!1)}).call(this,o)},c=function(){var e;if(arguments.length)for(e=0;e<arguments.length;++e)if(/\s/.test(arguments[e])){var o=new SyntaxError('String "'+arguments[e]+'" contains an invalid character');throw o.code=5,o.name="InvalidCharacterError",o}if(i!==t[n]){r=(""+t[n]).replace(/^\s+|\s+$/g,"").split(/\s+/),l={};for(var e=0;e<r.length;++e)l[r[e]]=!0;s=r.length,a.call(this)}};return c.call(this),e(this,"length",function(){return c.call(this),s}),this.toLocaleString=this.toString=function(){return c.call(this),r.join(" ")},this.item=function(t){return c.call(this),r[t]},this.contains=function(t){return c.call(this),!!l[t]},this.add=function(){c.apply(this,arguments);for(var e,i=0;i<arguments.length;++i)e=arguments[i],l[e]||(r.push(e),l[e]=!0);s!==r.length&&(s=r.length>>>0,t[n]=r.join(" "),a.call(this))},this.remove=function(){c.apply(this,arguments);for(var e={},i=0;i<arguments.length;++i)e[arguments[i]]=!0,delete l[arguments[i]];for(var o=[],i=0;i<r.length;++i)e[r[i]]||o.push(r[i]);r=o,s=o.length>>>0,t[n]=r.join(" "),a.call(this)},this.toggle=function(t,e){return c.apply(this,[t]),void 0!==e?e?(this.add(t),!0):(this.remove(t),!1):l[t]?(this.remove(t),!1):(this.add(t),!0)},function(t,e){if(e)for(var n="item contains add remove toggle toString toLocaleString".split(" "),i=0;7>i;++i)e(t,n[i],{enumerable:!1})}(this,Object.defineProperty),this};i.polyfill=!0,window.DOMTokenList=i;var r=function(n,l,s){e(n.prototype,l,function(){var n,o="__defining_"+l+"__";if(this[o])return n;if(this[o]=!0,!1===t){for(var a,c=r.mirror=r.mirror||document.createElement("div"),h=c.childNodes,u=h.length,f=0;u>f;++f)if(h[f].reflectedElement===this){a=h[f];break}a||(a=document.createElement("div"),c.appendChild(a)),n=i.call(a,this,s)}else n=new i(this,s);return e(this,l,function(){return n}),delete this[o],n},!0)};r(Element,"classList","className"),r(HTMLLinkElement,"relList","rel"),r(HTMLAnchorElement,"relList","rel"),r(HTMLAreaElement,"relList","rel")}();


/** UNCOMPRESSED: */
if(!window.DOMTokenList)
(function(){


    /** Ascertain browser support for Object.defineProperty */
    var dpSupport   =   "defineProperty" in Object || "__defineGetter__" in Object.prototype || null;


    /** Wrapper for Object.defineProperty that falls back to using the legacy __defineGetter__ method if available. */
    var defineGetter    =   function(object, name, fn, configurable){
        if(Object.defineProperty)
            Object.defineProperty(object, name, {
                configurable:   false === dpSupport ? true : !!configurable,
                get:            fn
            });

        else object.__defineGetter__(name, fn);
    };


    /** Ensure the browser allows Object.defineProperty to be used on native JavaScript objects. */
    if(dpSupport)
        try{ defineGetter({}, "support"); }
        catch(e){ dpSupport = false; }



    var DOMTokenList    =   function(el, prop){

        /** Private variables */
        var tokens      =   [],
            tokenMap    =   {},
            length      =   0,
            maxLength   =   0,
            lastValue,


        reindex     =   function(){

            /** Define getter functions for array-like access to the tokenList's contents. */
            if(length >= maxLength){
                for(; maxLength < length; ++maxLength){

                    (function(i){
                        defineGetter(this, i, function(){ preop.call(this); return tokens[i]; }, false);
                    }).call(this, maxLength);
                }
            }
        },


        /** Helper function called at the start of each class method. Internal use only. */
        preop   =   function(){
            var i;

            /** Validate the token/s passed to an instance method, if any. */
            if(arguments.length){
                for(i = 0; i < arguments.length; ++i)
                    if(/\s/.test(arguments[i])){
                        var error   =   new SyntaxError('String "' + arguments[i] + '" contains an invalid character');
                        error.code  =   5;
                        error.name  =   "InvalidCharacterError";
                        throw error;
                    }
            }


            /** Check if the subject attribute of the target element has changed since the tokenList was last used. If so, repopulate the internal token lists. */
            if(lastValue !== el[prop]){
                tokens      =   ("" + el[prop]).replace(/^\s+|\s+$/g, "").split(/\s+/);
                tokenMap    =   {};
                for(var i = 0; i < tokens.length; ++i)
                    tokenMap[tokens[i]] =   true;
                length  =   tokens.length;
                reindex.call(this);
            }
        };



        /** Populate our internal token lists if the targeted attribute of the subject element isn't empty. */
        preop.call(this);



        /** Returns the number of tokens in the underlying string. Read-only. */
        defineGetter(this, "length", function(){ preop.call(this); return length; });


        /** Override the default toString method to return a space-delimited list of tokens when typecast. */
        this.toLocaleString =
        this.toString       =   function(){
            preop.call(this);
            return tokens.join(" ");
        };



        /** Returns an item in the list by its index (or undefined if the number is greater than or equal to the length of the list) */
        this.item   =   function(idx){
            preop.call(this);
            return tokens[idx];
        };


        /** Returns TRUE if the underlying string contains `token`; otherwise, FALSE. */
        this.contains   =   function(token){
            preop.call(this);
            return !!tokenMap[token];
        };



        /** Adds one or more tokens to the underlying string. */
        this.add    =   function(){
            preop.apply(this, arguments);

            for(var token, i = 0; i < arguments.length; ++i){
                token   =   arguments[i];
                if(!tokenMap[token]){
                    tokens.push(token);
                    tokenMap[token] =   true;
                }
            }

            /** Update the targeted attribute of the attached element if the token list's changed. */
            if(length !== tokens.length){
                length      =   tokens.length >>> 0;
                el[prop]    =   tokens.join(" ");
                reindex.call(this);
            }
        };


        /** Removes one or more tokens from the underlying string. */
        this.remove =   function(){
            preop.apply(this, arguments);

            /** Build a hash of token names to compare against when recollecting our token list., */
            for(var ignore = {}, i = 0; i < arguments.length; ++i){
                ignore[arguments[i]]    =   true;
                delete tokenMap[arguments[i]];
            }

            /** Run through our tokens list and reassign only those that aren't defined in the hash declared above. */
            for(var t = [], i = 0; i < tokens.length; ++i)
                if(!ignore[tokens[i]]) t.push(tokens[i]);

            tokens  =   t;
            length  =   t.length >>> 0;

            /** Update the targeted attribute of the attached element. */
            el[prop]    =   tokens.join(" ");
            reindex.call(this);
        };


        /** Adds or removes a token depending on whether it's already contained within the token list. */
        this.toggle =   function(token, force){
            preop.apply(this, [token]);

            /** Token state's being forced. */
            if(undefined !== force){
                if(force)   {   this.add(token);    return true;    }
                else        {   this.remove(token); return false;   }
            }

            /** Token already exists in tokenList. Remove it, and return FALSE. */
            if(tokenMap[token]){
                this.remove(token);
                return false;
            }

            /** Otherwise, add the token and return TRUE. */
            this.add(token);
            return true;
        };


        /** Mark our newly-assigned methods as non-enumerable. */
        (function(o, defineProperty){
            if(defineProperty)
                for(var methods = "item contains add remove toggle toString toLocaleString".split(" "), i = 0; i < 7; ++i)
                    defineProperty(o, methods[i], {enumerable: false});
        }(this, Object.defineProperty));
        return this;
    };

    DOMTokenList.polyfill   =   true;
    window.DOMTokenList     =   DOMTokenList;



    /** Polyfill our properties */
    var addProp =   function(o, name, attr){

        defineGetter(o.prototype, name, function(){
            var tokenList, cork = "__defining_" + name + "__";
            if(this[cork]) return tokenList;

            this[cork]  =   true;


            /** IE8 can't define properties on native JavaScript objects, so we'll use a retarded hack instead. */
            if(false === dpSupport){

                var mirror = addProp.mirror     =   addProp.mirror || document.createElement("div"),
                    reflections                 =   mirror.childNodes,

                    /** Iterator variables */
                    l   = reflections.length,
                    i   = 0,
                    visage;

                for(; i < l; ++i)
                    if(reflections[i].reflectedElement === this){
                        visage  =   reflections[i];
                        break;
                    }

                /** Couldn't find an element's reflection inside the mirror. Materialise one. */
                if(!visage){
                    visage  =   document.createElement("div");
                    /*visage.IE8_GETTER_REFLECTION  =   this;*/
                    mirror.appendChild(visage);
                }

                tokenList   =   DOMTokenList.call(visage, this, attr);
            }

            else tokenList  =   new DOMTokenList(this, attr);


            defineGetter(this, name, function(){ return tokenList; });
            delete this[cork];

            return tokenList;
        }, true);
    };

    addProp( Element,           "classList",    "className");
    addProp( HTMLLinkElement,   "relList",      "rel");
    addProp( HTMLAnchorElement, "relList",      "rel");
    addProp( HTMLAreaElement,   "relList",      "rel");
}());