<!DOCTYPE html> <html> <body> <h1>JavaScript 运算符</h1> <h2>typeof 运算符</h2> <p>typeof 操作符返回变量、对象、函数或表达式的类型:</p> <p id="demo"></p> <script> document.getElementById("demo").innerHTML = "'Bill' 是 " + typeof "Bill" + "<br>" + "3.14 是 " + typeof 3.14 + "<br>" + "NaN 是 " + typeof NaN + "<br>" + "false 是 " + typeof false + "<br>" + "[1, 2, 3, 4] 是 " + typeof [1, 2, 3, 4] + "<br>" + "{name:'Bill', age:19} 是 " + typeof {name:'Bill', age:19} + "<br>" + "new Date() 是 " + typeof new Date() + "<br>" + "function () {} 是 " + typeof function () {} + "<br>" + "myCar 是 " + typeof myCar + "<br>" + "null 是 " + typeof null; </script> </body> </html>