Is the value sent only if the checkbox is checked?
Yes, standard behaviour is the value is only sent if the checkbox is checked. This typically means you need to have a way of remembering what checkboxes you are expecting on the server side since not all the data comes back from the form. The default value is always “on”, this should be consistent across browsers.
When do you skip checkboxes in HTML4?
Thus unchecked checkboxes are skipped during form data construction. Similar behavior is required under HTML4. It’s reasonable to expect this behavior from all compliant browsers. Checkboxes are posting value ‘on’ if and only if the checkbox is checked.
When does a checkbox become valid for submission?
Checkboxes (and radio buttons) are on/off switches that may be toggled by the user. A switch is “on” when the control element’s checked attribute is set. When a form is submitted, only “on” checkbox controls can become successful. A successful control is “valid” for submission.
When do checkbox inputs only post data in HTML?
When a form is submitted, only “on” checkbox controls can become successful. In HTML, each element is associated with a single (but not unique) name and value pair. This pair is sent in the subsequent request (in this case, a POST request body) only if the is “successful”.
How to update the value of a checkbox?
The workaround is to add a hidden field to the page that represents the state of the checkbox, then update the field’s value to “ON” or “OFF” for example, whenever the checkbox is clicked. Then on the server you check the value of the hidden field, not the checkbox itself, as the hidden field is always posted.
What happens if checkbox is not checked in HTML5?
If checkbox isn’t checked then it doesn’t contribute to the data sent on form submission. HTML5 section 4.10.22.4 Constructing the form data set describes the way form data is constructed: If any of the following conditions are met, then skip these substeps for this element: […]