叮叮当当

document.onkeydown=function(){if(event.keyCode==8)return false;};
这是屏蔽退格键的

http://www.cnblogs.com/88223100/archive/2008/08/10/1264699.html


<script>
document.onkeydown   =   function(){
        if(event.srcElement.tagName.toLowerCase()   !=   "input"){
                if(event.keyCode   ==  
                        event.returnValue   =   false;
        }
}
</script>
<input   id= "txt "   value= "aaa ">