1. function form() {
2.   var fname = document.getElementById("ifname").value;
3.   var email = document.getElementById("iemail").value;
4.   var mobile = document.getElementById("imob").value;
5.   var pass = document.getElementById("ipass").value;
6.   var namepattern = /[a-zA-Z.]/;
7.   var emailpattern = /(cse|eee|law)_\d{10}@lus\.ac\.bd/;
8.   var mobpattern = /(\+88)?-?01[3-9]\d{8}/;
9.   var passpattern =
10.     /((?=.*[A-Z])(?=.*[a-z])(?=.*[0-9])(?=.*[!@#$%^&*><?()*&+_])).{8,20}/;
11.  
12.   //first name
13.   if (fname.length < 2 || fname.length > 20) {
14.     // alert&#40;"length must be 2-20"&#41;;
15.     document.getElementById("efname")[removed] = "length must be 2-20";
16.     return false;
17.   } else if (!fname.match(namepattern)) {
18.     // alert&#40;"invalid input"&#41;;
19.     document.getElementById("efname")[removed] = "invalid input";
20.     return false;
21.   } else {
22.     // alert&#40;"valid"&#41;;
23.     document.getElementById("efname")[removed] = "";
24.   }
25.   //email
26.   if (!email.match(emailpattern)) {
27.     // alert&#40;"invalid input"&#41;;
28.     document.getElementById("eemail")[removed] = "invalid input";
29.     return false;
30.   } else {
31.     // alert&#40;"valid"&#41;;
32.     document.getElementById("eemail")[removed] = "";
33.   }
34.   //mobile
35.   if (!mobile.match(mobpattern)) {
36.     // alert&#40;"invalid input"&#41;;
37.     document.getElementById("emob")[removed] = "invalid input";
38.     return false;
39.   } else {
40.     // alert&#40;"valid"&#41;;
41.     document.getElementById("emob")[removed] = "";
42.   }
43.  
44.   //password
45.   if (!pass.match(passpattern)) {
46.     // alert&#40;"invalid input"&#41;;
47.     document.getElementById("epass")[removed] = "invalid input";
48.     return false;
49.   } else {
50.     // alert&#40;"valid"&#41;;
51.     document.getElementById("epass")[removed] = "";
52.   }
53. }
54.