How to check if a checkbox is checked or not using jQuery?

How can I determine if a checkbox is checked or not? I have tried using various methods but have not been able to successfully determine the checked state of the checkbox.

There are many options to check whether a check box is checked. Here are a few examples below.

jQuery is() method

if( $(this).is(':checked') ){
    // do something
}

jQuery prop() method

if( $(this).prop('checked') == true ){
    // do something
}

jQuery check length

if ( $('input[type="checkbox"]:checked').length ) {
    // do something
}

Pure JavaScript

if( document.getElementById('checkboxid').checked ) {
    // do something
}

You can use any of the solutions above.