1//using plane javascript
2if(document.getElementById('on_or_off_checkbox').checked) {
3 //I am checked
4}
5
6//using jQuery
7if($('#on_or_off_checkbox').is(':checked')){
8 //I am checked
9}
1$( "SELECTOR" ).attr( "checked" ) // Returns ‘true’ if present on the element, returns undefined if not present
2$( "SELECTOR" ).prop( "checked" ) // Returns true if checked, false if unchecked.
3$( "SELECTOR" ).is( ":checked" ) // Returns true if checked, false if unchecked.
1if ($('[name="your_input_checkbox_name"]').is(":checked"))
2{
3 // it is checked
4} else {
5 // it isn't checked
6}