I also can't understand that g_form.getControl('applicantdept')&g_form.getValue('variables.approver') don't return true&false why it can be written as below?

function onLoad(){
var applicantdept_element = g_form.getControl('applicantdept');

if(!applicantdept_element){

***************************

}
var approver_name = g_form.getValue('variables.approver');
if(!approver_name){

******************

}