<!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> var num = 10; console.log(typeof num); // number var str = 'pink'; console.log(typeof str); // string var flag = true; console.log(typeof flag); // boolean var vari = undefined; console.log(typeof vari); // undefined var timer = null; console.log(typeof timer); // object // prompt 取过来的值是 字符型的 var age = prompt('请输入您的年龄'); console.log(age); console.log(typeof age); </script> </head> <body> </body> </html>