兩個(gè)input框，對(duì)其中一個(gè)輸入框監(jiān)聽(tīng)keydown事件，將其值賦給給另一個(gè)框，但是值總是差一位，用keyup事件沒(méi)有問(wèn)題

<div class="test">
    <input class="test1" type="text" name="test1">
    <input class="test2" type="text" name="test2">
</div>
<script type="text/javascript">
    var test1 = document.getElementsByClassName('test1')[0];
    var test2 = document.getElementsByClassName('test2')[0];

    test1.addEventListener('keydown', function(e) {
        test2.value = e.target.value;
    })
</script>