常用JavaScript 方法

-----------------------------------  1：复选框全选

<script language="javascript">
function selectAll(){
var al = document.getElementById("all");

/*方式1
if(al.checked == true){
var cbs = document.getElementsByName("cb");
for(var i = 0; i < cbs.length; i++){
cbs[i].checked = true;
}
}else{
var cbs = document.getElementsByName("cb");
for(var i = 0; i < cbs.length; i++){
cbs[i].checked = false;
}
}
*/

                  
                  //优化后的方式2
var cbs = document.getElementsByName("cb");
for(var i = 0; i < cbs.length; i++){
cbs[i].checked = al.checked;
}



}
</script>
</head>

<form id="form1" name="form1" method="post" action="">
  <p>
    全选
      <input type="checkbox" name="checkbox2" value="checkbox" id="all" onclick="selectAll();"/>
  </p>
  <p>
    <input type="checkbox" name="cb" value="checkbox" />
    <input type="checkbox" name="cb" value="checkbox" /> 
    <input type="checkbox" name="cb" value="checkbox" /> 
    <input type="checkbox" name="cb" value="checkbox" /> 
    <input type="checkbox" name="cb" value="checkbox" /> 
    <input type="checkbox" name="cb" value="checkbox" /> 
    <input type="checkbox" name="cb" value="checkbox" /> 
    <input type="checkbox" name="cb" value="checkbox" /> 
    <input type="checkbox" name="cb" value="checkbox" /> 
    <input type="checkbox" name="cb" value="checkbox" />
  </p>
</form>

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