<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>菜鸟教程(runoob.com)</title> </head> <body> <p>局部变量在声明的函数外不可以访问。</p> <p id="demo"></p> <script> myFunction(); document.getElementById("demo").innerHTML = "carName 的类型是：" + typeof carName; function myFunction() { var carName = "Volvo"; } </script> </body> </html>
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>菜鸟教程(runoob.com)</title> </head> <body> <p>全局变量在任何脚本和函数内均可访问。</p> <p id="demo"></p> <script> var carName = "Volvo"; myFunction(); function myFunction() { document.getElementById("demo").innerHTML = "我可以显示 " + carName; } </script> </body> </html>
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>菜鸟教程(runoob.com)</title> </head> <body> <p> 如果你的变量没有声明，它将自动成为全局变量： </p> <p id="demo"></p> <script> myFunction(); document.getElementById("demo").innerHTML = "我可以显示 " + carName; function myFunction() { carName = "Volvo"; } </script> </body> </html>
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>菜鸟教程(runoob.com)</title> </head> <body> <p> 在 HTML 中, 所有全局变量都会成为 window 变量。 </p> <p id="demo"></p> <script> myFunction(); document.getElementById("demo").innerHTML = "我可以显示 " + window.carName; function myFunction() { carName = "Volvo"; } </script> </body> </html>
