keyCodeToChar = {8:"Backspace",9:"Tab",13:"Enter",16:"Shift",17:"Ctrl",18:"Alt",19:"Pause/Break",20:"Caps Lock",27:"Esc",32:"Space",33:"Page Up",34:"Page Down",35:"End",36:"Home",37:"Left",38:"Up",39:"Right",40:"Down",45:"Insert",46:"Delete",48:"0",49:"1",50:"2",51:"3",52:"4",53:"5",54:"6",55:"7",56:"8",57:"9",65:"A",66:"B",67:"C",68:"D",69:"E",70:"F",71:"G",72:"H",73:"I",74:"J",75:"K",76:"L",77:"M",78:"N",79:"O",80:"P",81:"Q",82:"R",83:"S",84:"T",85:"U",86:"V",87:"W",88:"X",89:"Y",90:"Z",91:"Windows",93:"Right Click",96:"Numpad 0",97:"Numpad 1",98:"Numpad 2",99:"Numpad 3",100:"Numpad 4",101:"Numpad 5",102:"Numpad 6",103:"Numpad 7",104:"Numpad 8",105:"Numpad 9",106:"Numpad *",107:"Numpad +",109:"Numpad -",110:"Numpad .",111:"Numpad /",112:"F1",113:"F2",114:"F3",115:"F4",116:"F5",117:"F6",118:"F7",119:"F8",120:"F9",121:"F10",122:"F11",123:"F12",144:"Num Lock",145:"Scroll Lock",182:"My Computer",183:"My Calculator",186:";",187:"=",188:",",189:"-",190:".",191:"/",192:"`",219:"[",220:"\\",221:"]",222:"'"};
keyCharToCode = {"Backspace":8,"Tab":9,"Enter":13,"Shift":16,"Ctrl":17,"Alt":18,"Pause/Break":19,"Caps Lock":20,"Esc":27,"Space":32,"Page Up":33,"Page Down":34,"End":35,"Home":36,"Left":37,"Up":38,"Right":39,"Down":40,"Insert":45,"Delete":46,"0":48,"1":49,"2":50,"3":51,"4":52,"5":53,"6":54,"7":55,"8":56,"9":57,"A":65,"B":66,"C":67,"D":68,"E":69,"F":70,"G":71,"H":72,"I":73,"J":74,"K":75,"L":76,"M":77,"N":78,"O":79,"P":80,"Q":81,"R":82,"S":83,"T":84,"U":85,"V":86,"W":87,"X":88,"Y":89,"Z":90,"Windows":91,"Right Click":93,"Numpad 0":96,"Numpad 1":97,"Numpad 2":98,"Numpad 3":99,"Numpad 4":100,"Numpad 5":101,"Numpad 6":102,"Numpad 7":103,"Numpad 8":104,"Numpad 9":105,"Numpad *":106,"Numpad +":107,"Numpad -":109,"Numpad .":110,"Numpad /":111,"F1":112,"F2":113,"F3":114,"F4":115,"F5":116,"F6":117,"F7":118,"F8":119,"F9":120,"F10":121,"F11":122,"F12":123,"Num Lock":144,"Scroll Lock":145,"My Computer":182,"My Calculator":183,";":186,"=":187,",":188,"-":189,".":190,"/":191,"`":192,"[":219,"\\":220,"]":221,"'":222};

keyCodeToChar = {8:"Backspace",9:"Tab",13:"Enter",16:"Shift",17:"Ctrl",18:"Alt",19:"Pause/Break",20:"Caps Lock",27:"Esc",32:"Space",33:"Page Up",34:"Page Down",35:"End",36:"Home",37:"Left",38:"Up",39:"Right",40:"Down",45:"Insert",46:"Delete",48:"0",49:"1",50:"2",51:"3",52:"4",53:"5",54:"6",55:"7",56:"8",57:"9",65:"A",66:"B",67:"C",68:"D",69:"E",70:"F",71:"G",72:"H",73:"I",74:"J",75:"K",76:"L",77:"M",78:"N",79:"O",80:"P",81:"Q",82:"R",83:"S",84:"T",85:"U",86:"V",87:"W",88:"X",89:"Y",90:"Z",91:"Windows",93:"Right Click",96:"Numpad 0",97:"Numpad 1",98:"Numpad 2",99:"Numpad 3",100:"Numpad 4",101:"Numpad 5",102:"Numpad 6",103:"Numpad 7",104:"Numpad 8",105:"Numpad 9",106:"Numpad *",107:"Numpad +",109:"Numpad -",110:"Numpad .",111:"Numpad /",112:"F1",113:"F2",114:"F3",115:"F4",116:"F5",117:"F6",118:"F7",119:"F8",120:"F9",121:"F10",122:"F11",123:"F12",144:"Num Lock",145:"Scroll Lock",182:"My Computer",183:"My Calculator",186:";",187:"=",188:",",189:"-",190:".",191:"/",192:"`",219:"[",220:"\\",221:"]",222:"'"};
keyCharToCode = {"Backspace":8,"Tab":9,"Enter":13,"Shift":16,"Ctrl":17,"Alt":18,"Pause/Break":19,"Caps Lock":20,"Esc":27,"Space":32,"Page Up":33,"Page Down":34,"End":35,"Home":36,"Left":37,"Up":38,"Right":39,"Down":40,"Insert":45,"Delete":46,"0":48,"1":49,"2":50,"3":51,"4":52,"5":53,"6":54,"7":55,"8":56,"9":57,"A":65,"B":66,"C":67,"D":68,"E":69,"F":70,"G":71,"H":72,"I":73,"J":74,"K":75,"L":76,"M":77,"N":78,"O":79,"P":80,"Q":81,"R":82,"S":83,"T":84,"U":85,"V":86,"W":87,"X":88,"Y":89,"Z":90,"Windows":91,"Right Click":93,"Numpad 0":96,"Numpad 1":97,"Numpad 2":98,"Numpad 3":99,"Numpad 4":100,"Numpad 5":101,"Numpad 6":102,"Numpad 7":103,"Numpad 8":104,"Numpad 9":105,"Numpad *":106,"Numpad +":107,"Numpad -":109,"Numpad .":110,"Numpad /":111,"F1":112,"F2":113,"F3":114,"F4":115,"F5":116,"F6":117,"F7":118,"F8":119,"F9":120,"F10":121,"F11":122,"F12":123,"Num Lock":144,"Scroll Lock":145,"My Computer":182,"My Calculator":183,";":186,"=":187,",":188,"-":189,".":190,"/":191,"`":192,"[":219,"\\":220,"]":221,"'":222};

function Keyboard() {
    this.KeyDown = function(key) {
        if (key instanceof Number) {
            key = keyCodeToChar[key];
        }
        if (this[key] === false || this[key] === null) {
            return false;
        }
        return true;
    }
}

Add Keyboard object to track current inputs