SO - 14725969

by Arun P Johny

HTML

<div id="general">
    <i>
        <span class="counter"></span>
    </i>
</div>

<input type="checkbox" class="select_all" />Select All <br />
<div id="general-content">
    <input type="checkbox" name="wpmm[]" /><br />
    <input type="checkbox" name="wpmm[]" /><br />
    <input type="checkbox" name="wpmm[]" /><br />
    <input type="checkbox" name="wpmm[]" /><br />
</div>

JavaScript

$('#general i .counter').text(' ');

var fnUpdateCount = function() {
	var generallen = $("#general-content input[name='wpmm[]']:checked").length;
    console.log(generallen,$("#general i .counter") )
	if (generallen > 0) {
		$("#general i .counter").text('(' + generallen + ')');
	} else {
		$("#general i .counter").text(' ');
	}
};

$("#general-content input:checkbox").on("change", function() {
			fnUpdateCount();
		});

$('.select_all').change(function() {
			var checkthis = $(this);
			var checkboxes = $("#general-content input:checkbox");

			if (checkthis.is(':checked')) {
				checkboxes.prop('checked', true);
			} else {
				checkboxes.prop('checked', false);
			}
            fnUpdateCount();
		});