源代码
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>享学课堂</title> </head> <body> <p>变量可以通过设置值为<b>undefined</b>来清空它.</p> <p id="demo"></p> <script> var person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"}; var person = undefined; document.getElementById("demo").innerHTML = person + "<br>" + typeof person; </script> </body> </html>
运行结果