Hectorhua 2019-04-25
加速运动,即一个物体运动时速度越来越快;减速运动,即一个物体运动时速度越来越慢。现在用Javascript来模拟这两个效果,原理就是用setInterval或setTimeout动态改变一个元素与另外一个元素的距离,如xxx.style.left或xxx.style.marginLeft,然后每次运动后都使速度增加,这样加速运动的效果就出现了,减速运动是同样的道理。
下面是两个示例:
加速运动
代码如下:
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Javascript加速运动</title> <style type="text/css"> * {margin: 0; padding: 0;} .div1 {width: 100px; height: 100px; background: #f60 url(qiuweiguan.gif) no-repeat center center;} </style> <script type="text/javascript"> var $$ = function (id) { return document.getElementById(id); } window.onload = function () { var oBtn = $$("btn1"); var oDiv = $$("div1"); var timer = null; var speed = 0; oBtn.onclick = function () { clearInterval(timer); timer = setInterval(function () { speed ++; oDiv.style.marginLeft = oDiv.offsetLeft + speed + "px"; }, 30); } } </script> </head> <body id = "body"> <button id="btn1" class="btn1">GO</button> <div id="div1" class="div1"></div> </body> </html>
注:本示例中,点击GO后,div块会一直向右做加速运动
减速运动
代码如下:
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Javascript减速运动</title> <style type="text/css"> * {margin: 0; padding: 0;} .div1 {width: 100px; height: 100px; background: #f60 url(qiuweiguan.gif) no-repeat center center;} </style> <script type="text/javascript"> var $$ = function (id) { return document.getElementById(id); } window.onload = function () { var oBtn = $$("btn1"); var oDiv = $$("div1"); var timer = null; var speed = 30; oBtn.onclick = function () { clearInterval(timer); timer = setInterval(function () { speed ― ; oDiv.style.marginLeft = oDiv.offsetLeft + speed + "px"; }, 30); } } </script> </head> <body id = "body"> <button id="btn1" class="btn1">GO</button> <div id="div1" class="div1"></div> </body> </html>
注:本示例中,点击GO后,div块会一直向右做减速运动,直到速度减为零后,速度变为负值,再向左做加速运动