function isIE(){
    return /msie/i.test(navigator.userAgent) && !/opera/i.test(navigator.userAgent);
}

function isOpera(){
    return /opera/i.test(navigator.userAgent);
}

function isSafari(){
    return /safari/i.test(navigator.userAgent);
}


function isIE6(){
    return navigator.userAgent.toLowerCase().indexOf('msie 6') != -1;
}

function isChrome(){
    var versionIndex = navigator.userAgent.indexOf('Chrome');
    if (versionIndex >= 0) return true;
    return false;
}