01.<html>
02.<head>
03.<title>ThaiCreate.Com Tutorial</title>
04.</head>
05.<body>
06.<form name="frmMain" action="" method="post" OnSubmit="return chkSubmit();">
07.<script language="JavaScript">
08. function chkSubmit()
09. {
10. if(isNaN(document.frmMain.txtNumber.value))
11. {
12. alert('Please input Number only.');
13. return false;
14. }
15. }
16.</script>
17.Input Number <input type="text" name="txtNumber" value="">
18.<input type="submit" name="btnSubmit" value="Submit">
19.</form>
20.</body>
21.</html>
