演示代码:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<script type="text/javascript">
// 2,自增++、自减--
var a = 3;
// a++;// 值为4
// ++a;// 值为4
// document.write(a);
// var b = 5*a++;// ++在后,先参与运算,再自增,
// document.write(a,"<br />",b)
var b = 5*++a;// ++在前,先自增,再参与运算,
document.write(a,"<br />",b)
</script>
</head>
<body>
</body>
</html>