var isCtrl = false;
var key = {ctrl: 17, left: 37, right: 39, home: 36, end: 35}

$(document).keyup(function (e) {

    if(e.which == key.ctrl) {
        isCtrl=false;
    }

}).keydown(function (e) {
    if(e.which == key.ctrl) { 
        isCtrl=true;
    }

    if(e.which == key.left && isCtrl == true) {
            if ($("a#firstlink").attr('href') != undefined) {
                location.href = $('a#firstlink').attr('href'); 
            }
    } else if (e.which == key.left && isCtrl == false) {
            if ($("a#prevlink").attr('href') != undefined) {
                location.href = $('a#prevlink').attr('href'); 
            }
    }

    if(e.which == key.right && isCtrl == true) {
            if ($("a#lastlink").attr('href') != undefined) {
                location.href = $('a#lastlink').attr('href'); 
            }
    } else if (e.which == key.right && isCtrl == false){
            if ($("a#nextlink").attr('href') != undefined) {
                location.href = $('a#nextlink').attr('href'); 
            }
    }
});