jQueryUI Tooltip + JSON problems

Question

Good Day,

I'm having problems implementing jQueryUI Tooltip.

Here's my code:

$("input.tooltip").tooltip({ 
    content: function(response) {
        $.getJSON('tooltipcontent.json', function(data) {
            response($.map(data, function(item) { return item.foo; } ))
        });
                    return 'tooltip content';
    }
});

What I'm going to do? I'm going to create json document with text for all input's tooltips. I'm stuck cause tooltip is...empty.

Any ideas?

Tom.