Harvard Extension School
CSCI E-12 Fundamentals of Web Site Development | Spring 2020

## Check and Uncheck All

JavaScript:

Here we take advantage of an attribute value selector (`[name="how"]`) the ability to retrieve and set property values. Note too that we iterate through each of the checkboxes.

To read more about attributes vs properties in jQuery, see: .prop() and .attr()

Example 9.2 - Check/Uncheck all - Example 9.2 | Example 9.2 JSFiddle

- Markup
- Script
- Screenshot

    <form action="http://cscie12.dce.harvard.edu/echo" method="get">
    <h3>How did you hear about us?</h3><p>[<a href="#" id="checkall">check all</a>] [<a href="#" id="uncheckall">uncheck all</a>] [<a href="#" id="togglecheckboxes">toggle</a>]</p>
    <ul style="list-style: none;">
    <li>
    <input type="checkbox" name="how" value="radio"/>Radio</li>
    <li>
    <input type="checkbox" name="how" value="newspaper"/>Newspaper</li>
    <li>
    <input type="checkbox" name="how" value="magazine"/>Magazine</li>
    <li>
    <input type="checkbox" name="how" value="online"/>Online</li>
    <li>
    <input type="checkbox" name="how" value="friend"/>Friend</li>
    </ul>
    <input type="submit"/>
    </form>

In `script` element within `head` element (`<script type="text/javascript">`):

    $(document).ready(function() {
      console.log($('#input[name="how"]'));
      $('#checkall').click(function() {
        $('input[name="how"]').prop('checked',true);
        console.log('check all!');
      });
      $('#uncheckall').click(function() {
        $('input[name="how"]').prop('checked',false);
        console.log('uncheck all!');
      });
      $('#togglecheckboxes').click(function() {
        $('input[name=how]').each(function (i) {
          if ($(this).is(':checked')) {
            $(this).prop('checked',false);
          } else {
            $(this).prop('checked',true);
          }
        });
      });
     });

Copyright © David Heitmeyer