js_code_move/yunsu2.html at master · yutaolian/js_code_move · GitHub

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<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>运动框架---匀速运动2---终止条件（范围）</title>
</head>
<style>
    #div1{
        width: 200px;
        height: 200px;
        position: absolute;
        background-color: chocolate;
        left: 0px;
        top: 200px;
    }
</style>
<script>

    var timmer = null;

    function startMove(target){

        var oDiv = document.getElementById("div1");

        clearInterval(timmer);

        timmer = setInterval(function(){

            var speed = 0;

            if(oDiv.offsetLeft<target){
                speed = 7;
            }else{
                speed = -7;
            }

            //匀速运动的终止条件是距离足够近（在一定范围内便到达）
            if(Math.abs(oDiv.offsetLeft-target)<7){
                clearInterval(timmer);

                oDiv.style.left = target+'px';

            }else{
                oDiv.style.left = oDiv.offsetLeft+speed+"px";
            }
        },30);


    }

</script>
<body>
<p>
    <h3>匀速运动的停止条件</h3>
<h4>距离足够近，在一定范围内即可</h4>
</p>
<input type="button" value="MOVE" onclick="startMove(500)">
<div id="div1"></div>
<span style="width: 1px;height: 300px;left: 500px;position: absolute;background-color: black" ></span>
</body>
</html>