源代码
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>享学课堂</title> </head> <body> <h1>JavaScript 变量</h1> <p>如果你重新声明一个JavaScript变量，它不会失去它的值.</p> <p id="demo"></p> <script> var carName = "Volvo"; var carName; document.getElementById("demo").innerHTML = carName; </script> </body> </html>
运行结果