源代码:
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Wfuyu教程(wfuyu.com)</title> </head> <body> <p>设置参数的默认值。</p> <p id="demo"></p> <script> function myFunction(x, y) { if (y === undefined) { y = 0; } return x * y; } document.getElementById("demo").innerHTML = myFunction(4); </script> </body> </html>
运行结果：