笔记二

<input   onmouseover="sel(this,4)"   value="abcdefghijklmnopqrst">  
   
  <script   language=javascript>  
  function   sel(obj,num)  
  {  
      var   rng=obj.createTextRange()  
      var   sel   =   rng.duplicate();  
      sel.moveStart("character",   num);  
      sel.setEndPoint("EndToStart",   rng);  
      sel.select();  
  }  
  </script>

下拉开框：属性
document.forms["sss"].elements["sel"].value--选中value
sel.length
sel.selectedIndex'
sel.options.length
sel.option[i].selected
sel.options[sel.selectedindex].value

添加子项
sel.options[4] =new option(value,text)
                         = null
清除
sel.length=0
表单验证
<input type="submint" onclick = "return valuidate()"/>
<form action="aaaaaa.asp" onsubmit="return valuidate"/>