2012-8-1复选框全选

//点击父复选框时
   function clickParentBox(obj){
    var childbox = document.all("子ID");
    if(obj.checked)
     for(i = 0 ; i< childbox.length ; i++)
      childbox[i].checked = true;
    else
     for(i = 0 ; i< childbox.length ; i++)
      childbox[i].checked = false;
   }
  //点击子复选 框时
   function clickChildBox(){
    var parentbox = document.getElementById("父ID");
    var childbox = document.all("childBox");
    for(i = 0 ;i < childbox.length ; i++){
     if (!childbox[i].checked)
      parentbox.checked = false;
    }
   }