<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>练习题</title> </head> <style type="text/css"> .box { height: 200px; width: 200px; background: red; } </style> <body> <!--让一个200px的盒子以每秒10px的速度增大到400，再返回到200px--> <div class="box">这是200*200的盒子</div> <script type="text/javascript"> var box = document.getElementsByClassName(‘box‘)[0]; var speed = 0; function move1() { speed += 10; box.style.width = 200 + speed + ‘px‘; box.style.height = 200 + speed + ‘px‘; if(speed >= 200) { clearInterval(t1); function move2() { speed -= 10; box.style.width = 200 + speed + ‘px‘; box.style.height = 200 + speed + ‘px‘; if(speed <= 0) { clearInterval(t2); } }; var t2 = setInterval(move2, 200); }; }; var t1 = setInterval(move1, 200); </script> </body> </html>
将一个200*200的盒子以200ms/10px的速到增到到400px之后再以同样的方式缩放到原来的位置
原文：http://www.cnblogs.com/tanxiang6690/p/6863466.html