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How Can I Validate An Email Address In JavaScript?

- 1 answer

I'd like to check if the user input is an email address in JavaScript, before sending it to a server or attempting to send an email to it, to prevent the most basic mistyping. How could I achieve this?

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Answer

Using regular expressions is probably the best way. You can see a bunch of tests here (taken from chromium)

const validateEmail = (email) => {
  return String(email)
    .toLowerCase()
    .match(
      /^(([^<>()[\]\\.,;:\[email protected]"]+(\.[^<>()[\]\\.,;:\[email protected]"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/
    );
};

Here's the example of a regular expression that accepts unicode:

const re =
  /^(([^<>()[\]\.,;:\[email protected]\"]+(\.[^<>()[\]\.,;:\[email protected]\"]+)*)|(\".+\"))@(([^<>()[\]\.,;:\[email protected]\"]+\.)+[^<>()[\]\.,;:\[email protected]\"]{2,})$/i;

But keep in mind that one should not rely only upon JavaScript validation. JavaScript can easily be disabled. This should be validated on the server side as well.

Here's an example of the above in action:

const validateEmail = (email) => {
  return email.match(
    /^(([^<>()[\]\\.,;:\[email protected]\"]+(\.[^<>()[\]\\.,;:\[email protected]\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/
  );
};

const validate = () => {
  const $result = $('#result');
  const email = $('#email').val();
  $result.text('');

  if (validateEmail(email)) {
    $result.text(email + ' is valid :)');
    $result.css('color', 'green');
  } else {
    $result.text(email + ' is not valid :(');
    $result.css('color', 'red');
  }
  return false;
}

$('#email').on('input', validate);

And this is the html:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<label for="email">Enter an email address: </label>
<input id="email" />
<h2 id="result"></h2>
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source: stackoverflow.com
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