JS运动基础

让Div运动起来

运动中的bug：

1.不会停止

2.速度取某些值会无法停止

3.到达位置后在点击还会运动

4.重复点击速度加快

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #div1 {
            width: 200px;
            height: 200px;
            background: red;
            position: absolute;
            top: 50px;
            left: 0px;
        }
    </style>
    <script>
        window.onload = function () {
            var oBtn = document.getElementById('btn');var oDiv = document.getElementById('div1');
            var time = null;
            var spead = 1;
            oBtn.onclick = function () {
                clearInterval(time);//解决：重复点击速度加快
                time = setInterval(function () {
                    if (oDiv.offsetLeft >= 300) {//解决：spead取值----速度取某些值会无法停止
                        clearInterval(time)
                    }else{//到达位置后在点击还会运动
                        oDiv.style.left = oDiv.offsetLeft + spead + 'px'
                    }
                   
                }, 10)
            }
        }

    </script>
</head>

<body>
    <input id="btn" type="button" value="开始运动">
    <div id="div1"></div>
</body>

</html>

运动框架及应用

运动框架

1.在开始运动时，关闭已有定时器

2.把运动和停止隔开（if/else）

缓冲运动

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #div {
            width: 200px;
            height: 200px;
            background: red;
            position: absolute;
            top: 50px;
            left: 0;
        }
    </style>
    <script>
        window.onload = function () {
            var oBtn = document.getElementById('btn');
            var oDiv = document.getElementById('div');

            oBtn.onclick = function () {
                setInterval(function () {
                    //Math.ceil()向上取整
                    //Math.floor()向下取整
                    var speed = (300 - oDiv.offsetLeft) / 10;
                    speed = speed > 0 ? Math.ceil(speed) : Math.floor(speed)
                    oDiv.style.left = oDiv.offsetLeft + speed + 'px'
                    document.title = oDiv.offsetLeft + speed + 'px'
                }, 30)
            }

        }
    </script>
</head>

<body>
    <input id="btn" type="button" value="缓冲运动">
    <div id="div"></div>
</body>

</html>

右侧悬浮框

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #div{
            width: 200px;
            height: 100px;
            background: red;
            position: absolute;
            right: 0;
            bottom: 40%;
        }
    </style>
    <script>
        window.onscroll = function () {
            var oDiv = document.getElementById('div');
            var scrollTop = document.documentElement.scrollTop||document.body.scrollTop;
            //oDiv.style.top = (document.documentElement.clientHeight-oDiv.offsetHeight)/2+scrollTop+'px';
            startMove(parseInt((document.documentElement.clientHeight-oDiv.offsetHeight)/2+scrollTop));
        };
        var time = null;
        function startMove(iTarget){
            var oDiv = document.getElementById('div');
            //先停止计时器
            clearInterval(time);
            time = setInterval(function(){
                var speed = (iTarget-oDiv.offsetTop)/8;
                //判断speed的值上下取整
                speed = speed>0?Math.ceil(speed):Math.floor(speed);
                if(oDiv.offsetTop == iTarget){
                    clearInterval(time)
                }else{
                    oDiv.style.top = oDiv.offsetTop+speed+'px';
                }
            },30)
        }
    </script>
</head>
<body style="height: 2000px;">
    <div id="div"></div>
</body>
</html>

 

posted @ 2020-05-13 16:25  YH丶浩  阅读(108)  评论(0)  编辑  收藏  举报