How to validate input for only email friendly characters?

Question

I have JavaScript that validates whole email once entered:

function ValidateEmail(inputText)
{
    var mailformat = /^[a-zA-Z0-9.!#$%&’*+/=?^_`{|}~-]+@[a-zA-Z0-9-]+(?:\.[a-zA-Z0-9-]+)*$/
    if(inputText.value.match(mailformat))
    {
        alert("This is not a valid email address");
        return false;
        }
}

But how to check if single character is valid for email? So I want to prevent users to enter bad email characters. So function param would be these and should return false only if invalid character present:

m
my
mya
....
myaddress
....
myaddress@mail.com

Use `mailformat.test(inputText.value)`. See [RegExp.prototype.test()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/test) — Phil, Oct 22 '21 at 04:30
Why don't you use [``](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/email) and save yourself some trouble? — Andy, Oct 22 '21 at 04:35
@Andy, I think this will only work for client side validation and wont work in server side validation. — user11823877, Oct 22 '21 at 08:28
The OP has `React` as a tag so I assume the email address is coming from there. @user11823877 — Andy, Oct 22 '21 at 08:30
@Andy, got it. It also has nodejs tag. So just wanted to confirm. also I think we need to add pattern for type="email" to validate. — user11823877, Oct 22 '21 at 08:54
@John I think this expression should work for you: ^[A-z0-9]+[@]?[A-z0-9]+[.]?[A-z0-9]+$` — user11823877, Oct 22 '21 at 09:15

score 0 · Accepted Answer · answered Oct 23 '21 at 03:58

great answer: https://stackoverflow.com/a/46181/3764369

issues follows RFC 5322 https://emailregex.com/

w3 code example:

function ValidateEmail(inputText)
{
  var mailformat = /^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/;
  if(inputText.value.match(mailformat))
  {
    alert("Valid email address!");
    document.form.email.focus();
    return true;
  }
  else
  {
    alert("You have entered an invalid email address!");
    document.form.email.focus();
    return false;
  }
}

How to validate input for only email friendly characters?

1 Answers1