JavaScript checkbox全选与全不选的切换

  function select_all(){
var paras = document.getElementsByTagName("input");//全选checkbox
if(document.getElementById("all").checked==true){
for(var i=0; i<paras.length; i++){
var name = paras[i].getAttribute("name") //单选checkbox的name均delete_ids
if(name=="delete_ids") paras[i].setAttribute("checked",true);
}
}
else{
for(var i=0; i<paras.length; i++){
var name = paras[i].getAttribute("name")
if(name=="delete_ids") paras[i].setAttribute("checked",false);
}
}
}