按enter鍵，禁止換行

ue.addListener("keydown", function(type, event){   

//if (event.ctrlKey && event.which == 13) {//判斷ctrl 回車 發送

if (event.which == 13) {

     // 禁止換行

event.cancelBubble=true;

event.PReventDefault();

event.stopPropagation();

}