input checkbox is checked javascript code example

Example 1: How to check whether a checkbox is checked in jQuery?

//using plane javascript 
if(document.getElementById('on_or_off_checkbox').checked) {
    //I am checked
} 

//using jQuery
if($('#on_or_off_checkbox').is(':checked')){
    //I am checked
}

Example 2: js make checkbox checked

document.getElementById('your_checkbox').checked = true;