I am having trouble passing data retrieved from a $.post() function to use in other places in my code. I want to save the data as a variable and use it outside of the post() function. This is my code:

var last_update = function() {
$.post('/--/feed',
{func:'latest', who:$.defaults.login},
function($j){
            _j = JSON.parse($j);    
            alert(_j.text); // This one works    
        });
}
alert(_j.text); // This one doesn't
};

last_update(); //run the function

Please help!