javascript 按ctrl和enter键提交表单

<!DOCTYPE html>
<html lang="en">
<head>
   <meta charset="UTF-8">
   <title>测试</title>
</head>
<body>
     <textarea name="" id="tex2" cols="30" rows="10"></textarea>
   <input type="text" id="tex1" >
   <input type="button" id="btn1" value="提交">
   <script>
       var oBtn=document.getElementById('btn1');
       var oTex1=document.getElementById('tex1');
       var oTex2=document.getElementById('tex2');
       oBtn.onclick=function(){
           oTex2.value+=oTex1.value;
           oTex1.value='';
       }
       oTex1.onkeydown=function(ev){
           var oEvent=event||ev;
           if(oEvent.ctrlKey && oEvent.keyCode==13){
               oTex2.value+=oTex1.value;
               oTex1.value='';
               }
       }
   </script>
</body>
</html>

//oEvent.ctrlKey(ctrlKey、shiftKey、altKey)返回布尔值，altKey不常用