Result

jQuery

$(document).ready(function() {
         //queue()で処理を溜めてdequeue()で実行。3秒経ったらfadeOut()
        $("#timeout").fadeIn().queue(function() {
            setTimeout(function(){$("#timeout").dequeue();
            }, 3000);
        });
        $("#timeout").fadeOut();
});

css

#timeout{
    position:absolute;
    top:30px;
    left:50px;
    padding:20px; 
    border:1px solid #ddd;
    background:#eee;
}

html

<div id="timeout">
  <p>Time out</p>
</div>

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