变速动画函数封装 · js技术点

```html <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>title</title> <style> * { margin: 0; padding: 0; } div { margin-top: 20px; width: 200px; height: 100px; background-color: green; position: absolute; left: 0; top: 0; } </style> </head> <body> <input type="button" value="移动到400px" id="btn1"/> <input type="button" value="移动到800px" id="btn2"/> <div id="dv"></div> <script src="common.js"></script> <script> //点击按钮移动div my$("btn1").onclick = function () { animate(my$("dv"), 400); }; my$("btn2").onclick = function () { animate(my$("dv"), 800); }; //变速动画 function animate(element, target) { //清理定时器 clearInterval(element.timeId); element.timeId = setInterval(function () { //获取元素的当前位置 var current = element.offsetLeft; //移动的步数 var step = (target-current)/10; // Math.ceil是四舍五入，Math.floor是去下界 step = step > 0 ? Math.ceil(step) : Math.floor(step); current += step; element.style.left = current + "px"; if(current == target) { //清理定时器 clearInterval(element.timeId); } //测试代码: console.log("目标位置:"+target+",当前位置:"+current+",每次移动步数:"+step); }, 20); } </script> </body> </html> ```