jquery Cannot read property 'done' of undefined - avoid this

Question

I have a function which returns results (or not). The problem is when it does not return any value I get in the console the message

cannot read prope

Answer 1

You could just return a deferred, that way the done() callback won't generate errors, and you can choose to resolve it or not

if(items.length > 0){
    return $.ajax({
        url: 'response.php?type=getDelivery',
        type: 'POST',
        data: {content: items}
    });
}else{
    var def = new $.Deferred();
    def.resolve(false);
    return def;
}

FIDDLE