function isNewUsername(str){
    var result;
    $.post('/api/isnewusername', 
            {username:str},
            function(data) {
                result = data.result;
            }, 
            "json");
    return result;
}

So , my problem is very simple but I can not figure it out . I want to access result from the isnewusername function . I am very curious about answer because I spent 1 hour on it . Thank you