<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> <script> // 案例1 ： 结果是几？ function f1() { var num = 123; function f2() { var num = 0; console.log(num); // 站在目标出发，一层一层的往外查找 } f2(); } var num = 456; f1(); // 案例2 ：结果是几？ var a = 1; function fn1() { var a = 2; var b = '22'; fn2(); function fn2() { var a = 3; fn3(); function fn3() { var a = 4; console.log(a); //a的值 ? console.log(b); //b的值 ? } } } fn1(); </script> </head> <body> </body> </html>
