if radio is checked jquery code example

Example 1: jQuery check a radio button

// jQuery version 1.6 or above use:  
$("#myRadioID").prop("checked", true);
 
//jQuery versions below 1.6 use:
$("#myRadioID").attr('checked', 'checked');

Example 2: jquery radio button checked event

$('input:radio[name="postage"]').change(function(){

        if ($(this).val() == 'Yes') {
            //true
        }
        else {
            //false
        }
    });