自己写的js加密

<script>
function changeText(obj,str)
{  var len=str.length;
   var rs="";
   for(var i=0;i<len;i++){
          var k=str.substring(i,i+1);
          rs+= (i==0?"":i)+str.charCodeAt(i);
    

   }
  obj.value =rs;
}
function change(obj)
{ 
  obj.value ="********************";
  document.getElementById("uname").select();
}
</script>
name:<input id="uname" onblur="changeText(this,this.value);" onfocus="change(this)"/>