js 运动01

<input  type="button" onclick="startMove()" value="开始运动"/>
<div id="div1"></div>
<script>
    var timer = null;
    function startMove(){
        var oDiv = document.getElementById("div1");
        var iSpeed = 10;
        clearInterval(timer);//确保多次点击只开一个定时器
        timer = setInterval(function(){
            if(oDiv.offsetLeft >= 300){
                clearInterval(timer)
            }else{
                oDiv.style.left = oDiv.offsetLeft + iSpeed + ‘px‘;
            }
        },30);
    }
</script>