全局与局部
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>Insert title here</title> </head> <body> </body> <script type="text/javascript"> function show(){ var i=0;//局部变量 b=11; //不带var，全局变量 } show(); alert(b) alert(i); </script> </html>
闭包：局部变量不能访问，就用闭包
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>Insert title here</title> </head> <body> </body> <script type="text/javascript"> function show(){ var i=12; function inner(){ return i; } return inner; } var i=show(); alert(i()); </script> </html>