PROBLEM - Javascript / Jquery - Check all check boxes with a particular string in their Id

Problem

Check all check boxes with a particular string in their Id.

Solution Code

function checkBoxes(var string, var form){

     for (var i = 0; i < form.elements.length; i++ ) {
         if (form.elements[j].type == 'checkbox') {
             if(form.elements[j].id.indexOf("."+string) > -1) {
                $(form.elements[j]).attr("checked", true); 
            }
        }
    }

}