js判斷手機型號

由於oppo手機自帶瀏覽器的高度底部多了144px導航欄

所以：專門針對oppo手機做適配：

var dowphone = document.getElementById("dowphone");
function validBrowser(){   
    var u_agent = navigator.userAgent;    
    if(u_agent.indexOf('OPPO R7s Build')>-1){   
        dowphone.style.width = "54%";
        dowphone.style.marginLeft = "-27%";
    } 
}  
validBrowser();