abstract：<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <script src="https://code.jquery.com/jquery-3.1.1.min.js">
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<script src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
<title>Document</title>
<style>
a{font-size:40px;display:block;width:200px;height:200px;border-radius: 100px;line-height:200px;float: left;margin-right: 20px;background-color: #ccc;text-align: center;}
</style>
<script type="text/javascript">
function aa(idnum){
var len = document.getElementsByTagName(idnum).length
for(var i=0;i<len;i++)
{ document.getElementsByTagName(idnum)[i].style.backgroundColor = 'rgb('+Math.floor(Math.random()*256)+','+Math.floor(Math.random()*256)+','+Math.floor(Math.random()*256)+')'
document.getElementsByTagName(idnum).item(i).innerText = Math.floor(Math.random()*256);
}
}
$(function(){
aa('a')
})
</script>
</head>
<body>
<a href="#"></a>
<a href="#"></a>
<a href="#"></a>
<a href="#"></a>
</body>
</html>小球练习