Code to limit the maximum number of optional check boxes in javascript

Tip: you can modify some code before running

<script type="text/javascript">// Maximum number of options var maxSel = 5; // number of selected var num = 0; function doCheck (node) {if (node. checked) {// this check box is not selected. Click it and select if (num> = maxSel) {// if it has reached the upper limit, do not select this check box node. checked = false; alert ("You can select" + maxSel + "check boxes" for the maximum value);} else {// The maximum number of num ++;} has not been reached ;}} else {// you have already selected it. Click it and deselect num --;}}</script></td> </tr></table>

Tip: you can modify some code before running