[Octane]

<input type="checkbox" id="check1" name="check1" />
<input type="checkbox" id="check2" name="check2" />
<input type="checkbox" id="check3" name="check3" />
<input type="checkbox" id="check4" name="check4" />
<input type="checkbox" id="check5" name="check5" />
<input type="checkbox" id="check6" name="check6" />
<input type="checkbox" id="check7" name="check7" />
<input type="checkbox" id="check8" name="check8" />
<input type="checkbox" id="check9" name="check9" />
<input type="checkbox" id="check10" name="check10" />
<input type="button" id="check" value="Проверить" />
<script type="text/javascript">
    document.getElementById("check").onclick = function() {
		var checked = [];
		var count = 10;
		var i = 0;
		while(++i <= count) {
			if(document.getElementById("check" + i).checked) {
				checked.push(i);
			}
		}
		alert("Выбраны: " + checked);
    };
</script>