How to submit unchecked checkbox also

Question

If checkbox is not checked, clicking on form submit button does not submit any data.

Some checkboxes may be not present in form depending on form fields selected by

Answer 1

My shortest solution: use a checkbox's onchange() event to set a hidden sibling to 0 or 1. As follows:

var htm = '0?"checked":"")+' onchange="this.nextSibling.value=this.checked==true?1:0;" />';

Submit ONLY sends the hidden sibling, NOT the checkbox because it has no name attribute. So the above is serialized as "...&Gender=1..." or "...&Gender=0..." depending on isMale value.