js 判斷 瀏覽器

                   function userBrowser(){  
        var browserName=navigator.userAgent.toLowerCase();  
        if(/msie/i.test(browserName) && !/opera/.test(browserName)){  
            alert("IE");  
            return ;  
        }else if(/firefox/i.test(browserName)){  
            alert("Firefox");  
            return ;  
        }else if(/chrome/i.test(browserName) && /webkit/i.test(browserName) && /mozilla/i.test(browserName)){  
            alert("Chrome");  
            return ;  
        }else if(/opera/i.test(browserName)){  
            alert("Opera");  
            return ;  
        }else if(/webkit/i.test(browserName) &&!(/chrome/i.test(browserName) && /webkit/i.test(browserName) && /mozilla/i.test(browserName))){  
            alert("Safari");  
            return ;  
        }else{  
            alert("unKnow");  
        }  
    }