<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>函数function</title> <!-- function 函数名(参数1,参数2,.....参数n){ 执行语句1; 执行语句2; ... 执行语句n; } 调用函数的方法： 函数名(参数1,参数2;...); --> </head> <body> <script> function sum(a,b,c,d){ var y=a+b+c+d; document.write(y+"<br />"); var x=a-b; document.write(x+"<br />"); } sum(1,2,3,4);//页面中会有两个值 sum(1,3)//页面中会有两个值 </script> </body> </html>