test1

(function() {
    var e = document.getElementById('move');
    var sp = 4;
    var pos = 0;

    setInterval(move, 100);

    function move() {
        pos += sp;
        e.style.left = pos + 'px';
        if (pos % 200 == 0) sp *= (-1);
    }
})();

aaaa

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test