30秒到达战场
jQuery实现很简单啊,写了个demo给你<html><head> <meta charset="UTF-8"> <title>Document</title> <script src="//localhost/jquery-3.1.0.min.js"></script> <style> .wrap { position: relative; width: 500px; height: 500px; background-color: #eee; } .wrap div{ position: absolute; left: 50%; top: 50%; transform: translate(-50%,-50%); -webkit-transform: translate(-50%,-50%); -ms-transform: translate(-50%,-50%); width: 0px; height: 0px; background-color: red; } </style></head><body> <div class="wrap"> <div></div> </div></body><script>$(function(){ $('.wrap div').animate({height:'500px', width:'500px'},2000);})</script></html>