判断浏览器

function check(){
    if(window.navigator.userAgent.indexOf("MSIE 8.0")>=1){
    //如果浏览器为IE 8.0
        alert("ie8");
    }
    else if(window.navigator.userAgent.indexOf("MSIE 7.0")>=1){
    //如果浏览器为IE 7.0
        setActiveStyleSheet("IE7.0_index_layout.css");//设置css样式表
    }
    else if(window.navigator.userAgent.indexOf("TencentTraveler")>=1){
    //如果浏览器为腾讯TT
        setActiveStyleSheet("TT_index_layout.css");
    }
    else if(window.navigator.userAgent.indexOf("Maxthon")>=1){
    //如果浏览器为傲游
        setActiveStyleSheet("Maxthon_index_layout.css");
    }
    else if(window.navigator.userAgent.indexOf("MSIE 6.0")>=1){
    //如果浏览器为IE 6.0
        alert("ie6");
    }
    else if(window.navigator.userAgent.indexOf("Firefox")>=1){
    //如果浏览器为Firefox
        setActiveStyleSheet("FF_index_layout.css");
    }
    else if(window.navigator.userAgent.indexOf("Safari")>=1){
    //如果浏览器为Safari
        setActiveStyleSheet("Safari_index_layout.css");
    }
    else if(window.navigator.appName=="Opera"){
    //如果浏览器为Opera
        setActiveStyleSheet("Opera_index_layout.css");
    }
    else{
    //如果浏览器为其它
        setActiveStyleSheet("default_index_layout.css");
    }
}