javascript通过navigator.userAgent识别各种浏览器

function validBrowser(){
var u_agent = navigator.userAgent;
var browser_name=Failed to identify the browser;
if(u_agent.indexOf(Firefox)>-1){
browser_name=Firefox;
}else if(u_agent.indexOf(Chrome)>-1){
browser_name=Chrome;
}else if(u_agent.indexOf(Trident)>-1&&u_agent.indexOf(rv:11)>-1){
browser_name=IE11;
}else if(u_agent.indexOf(MSIE)>-1&&u_agent.indexOf(Trident)>-1){
browser_name=IE(8-10);
}else if(u_agent.indexOf(MSIE)>-1){
browser_name=IE(6-7);
}else if(u_agent.indexOf(Opera)>-1){
browser_name=Opera;
}else{
browser_name+=,info:+u_agent;
}
document.write(browser_name:+browser_name+<br>);
document.write(u_agent:+u_agent+<br>);
}