计算阶乘按钮
1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 2 <html xmlns="http://www.w3.org/1999/xhtml"> 3 <head> 4 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 5 <title>计算阶乘按钮</title> 6 </head> 7 8 <body> 9 10 <body> 11 <div style="margin:0px auto"> 12 这是计算阶乘的按钮: 13 <input type="button" value="点击输入整数" onclick="jiecheng()" /> 14 15 </div> 16 </body> 17 </html> 18 <script> 19 function jiecheng() 20 { 21 var a = prompt("输入数字吧","只能是整数哦！！！"); 22 if(isNaN(a)){ 23 alert("输入的不是整数"); 24 }else{ 25 var b =1; 26 for(var i=1;i<=a;i++){ 27 b= b*i; 28 } 29 alert(b); 30 } 31 } 32 </script> 33 34 35 36 </body> 37 </html>
显示的效果：
