选中/取消选中HTML表格的所有复选框

Question

I have got a HTML table which contain a check box in <TH> and other checkboxes in <TD> I want that all <TD> 's checkboxes should be checked /unchecked on basis of <TH> 's Check box; please help me resolve this. I wrote following code, but its not working:

   <script language="javascript" type="text/javascript">
  function SelectAll(id) {

    var frm = document.getElementById('tblemail');

    for (i=0;i<frm.elements.length;i++) {

        if (frm.elements[i].type == "checkbox") {

            frm.elements[i].checked = document.getElementById(id).checked;

        }

    }

} 

</script>

Answer 1

Try the following code

var frm = document.getElementById('tblemail').getElementsByTagName("input");
var len = frm.length;
var checkedStatus = document.getElementById(id).checked;

for (i=0;i<len;i++) 
{
    if (frm[i].type === "checkbox") 
    {    
        frm[i].checked = checkedStatus;
    }
}

Answer 2

你有没有尝试过

document.getElementById(id).checked = true