if element is checked jquery 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: jquery check if checkbox is checked

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

Example 3: how to check input is selected or not

var $boxes = $('input[name=thename]:checked');