<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>js教程之自增自检</title>
<script type="text/javascript">
var a=2;
//a++;
//++a;
//var b=1+a++;
//var b=5*a++;
var b=5*++a;
document.write(a,"</br>",b,"</br>")
</script>
</head>
<body>
++在前 先自增，再参与运算
++在后 先参与运算。再自增
</body>
</html>
