Need a regular expression for checking if an email is in the following format?

Question

if an email is in the format

[email protected]

coditions to check via the regex :

email has only 1 @

firstname.lastname

at the very end its either a .com or .net or .co.in

it should not accept emails like [email protected]

but should accept [email protected] or tcs.co.in

var empmail = '[email protected]'
var fullName = empmail.split('@')[0].split('.');
var firstName = fullName[0];
var lastName = fullName[ fullName.length-1 ] ;
var fullName = empmail.split('@')[0].split('.');

Answer 1

I believe you could try:

/^[^@]+\.[^@]+@[^@]+\.(com|net|co\.in)$/

let pattern = /^[^@]+\.[^@]+@[^@]+\.(com|net|co\.in)$/;
let testEmails = [
    "[email protected]",
    "[email protected]",
    "[email protected]",
    "[email protected]",
    "[email protected]",
    "[email protected]",
    "[email protected]",
    "[email protected]",
    "lastname@[email protected]"
];    
for (let i = 0; i < testEmails.length; i++) {
    console.log(`Email ${testEmails[i]}: ${pattern.test(testEmails[i])}`);
}

^

Start matching from the beginning of the string

[^@]+

One or more characters except @

\. 

Followed by a dot

[^@]+

Followed by one or more characters except @

@

Followed by @

[^@]+

Followed by one or more characters except @

\.

Followed by a dot

(com|net|co\.in)$

With the string ending in com, net, or co.in

If you want to restrict the input further so that there is only one dot in the firstname.lastname portion, you can change [^@] to [^@\.]

/^[^@\.]+\.[^@\.]+@[^@]+\.(com|net|co\.in)$/

let pattern = /^[^@\.]+\.[^@\.]+@[^@]+\.(com|net|co\.in)$/;
let testEmails = [
    "[email protected]",
    "[email protected]",
    "[email protected]",
    "[email protected]",
    "[email protected]",
    "[email protected]",
    "[email protected]",
    "[email protected]",
    "lastname@[email protected]"
];    
for (let i = 0; i < testEmails.length; i++) {
    console.log(`Email ${testEmails[i]}: ${pattern.test(testEmails[i])}`);
}