Check if checkbox is checked with jQuery

Question

How can I check if a checkbox in a checkbox array is checked using the id of the checkbox array?

I am using the following code, but it always returns the count of checked checkboxes regardless of id.

function isCheckedById(id) {
  alert(id);
  var checked = $("input[@id=" + id + "]:checked").length;
  alert(checked);

  if (checked == 0) {
    return false;
  } else {
    return true;
  }
}

Answer 1

$('#checkbox').is(':checked'); 

The above code returns true if the checkbox is checked or false if not.

Answer 2

You can try this:

<script>
function checkAllCheckBox(value)
{
   if($('#select_all_').is(':checked')){
   $(".check_").attr ( "checked" ,"checked" );
    }
    else
    {
        $(".check_").removeAttr('checked');
    }

 }

</script>
<input type="checkbox" name="chkbox" id="select_all_" value="1" />


<input type="checkbox" name="chkbox" class="check_" value="Apples" />
<input type="checkbox" name="chkbox" class="check_" value="Bananas" />
<input type="checkbox" name="chkbox" class="check_" value="Apples" />
<input type="checkbox" name="chkbox" class="check_" value="Bananas" />