How to check all chackbox onclick function via javascript

How to check all chackbox onclick function via javascript


<script type="application/javascript">

function checkAllbox(array_with_id_values)
{
    for (var i = 0, ilen = array_with_id_values.length; i < ilen; i++)
    {
        document.getElementById(array_with_id_values[i]).checked = true;
    }
}

</script>

<a href="javascript:void(0)" onClick="checkAllbox(['a1','a2','a3'])">select all</a>
Where a1,a2,a3 are different id checkbox