How do I validate an email address using a regex in JavaScript?

Question

I have the following email validation regex in JavaScript. It doesn't actually return anything, but I think it should (true or false).

What's wrong with this code?

function isEmail(aa){
    var testx=/^([^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c\x3e\x40\x5b-\x5d\x7f-\xff]+|\x22([^\x0d\x22\x5c\x80-\xff]|\x5c[\x00-\x7f])*\x22)(\x2e([^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c\x3e\x40\x5b-\x5d\x7f-\xff]+|\x22([^\x0d\x22\x5c\x80-\xff]|\x5c[\x00-\x7f])*\x22))*\x40([^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c\x3e\x40\x5b-\x5d\x7f-\xff]+|\x5b([^\x0d\x5b-\x5d\x80-\xff]|\x5c[\x00-\x7f])*\x5d)(\x2e([^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c\x3e\x40\x5b-\x5d\x7f-\xff]+|\x5b([^\x0d\x5b-\x5d\x80-\xff]|\x5c[\x00-\x7f])*\x5d))*$/
    return testx.test(aa);
}

<input type="text" name="email" id="email" onChange="isEmail(this.value)">

Do you think you'll maintain this regex ? You should read [this](http://davidcel.is/blog/2012/09/06/stop-validating-email-addresses-with-regex/). — Denys Séguret, May 07 '13 at 10:35
`onchange="return isEmail(this.value)"` - except I don't think you can cancel an onchange event. What do you expect to actually happen if the entered value fails the validation? — nnnnnn, May 07 '13 at 10:37
@Ghozt I think it'd be helpful for everyone if you broke the regex out into mulitple lines and tell us what you think each line should do, instead of dumping a regex that's hard to follow on others. — George Stocker, May 07 '13 at 11:12
See also [this question](http://stackoverflow.com/questions/201323/using-a-regular-expression-to-validate-an-email-address) for more regex suggestions. — legoscia, May 07 '13 at 12:32

Sudhir Bastakoti · Accepted Answer · 2013-05-07T10:41:52.657

1

you're testing for string 'aa', change

return testx.test('aa');

to

return testx.test(aa);

See: jsFiddle Demo

edited May 07 '13 at 10:41

answered May 07 '13 at 10:36

Sudhir Bastakoti

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I just saw that and edited it, it didnt help at all. The browser still does not return anything. – Ghozt May 07 '13 at 10:38
@Ghozt well, besides that it seems to work fine – Sudhir Bastakoti May 07 '13 at 10:41

Tim Bartsch · Answer 2 · 2013-05-07T13:02:17.733

Email validation via regular expressions seems to be extremely complicated.

If possible you should use HTML5 form validation

<input type="email">

diveintohtml5.info is a good place to learn more about form validation.

As far as I know the validation is a browser side thing that only works togehter with sumbit buttons. There is no javascript api for checking if a specific string is valid.

How do I validate an email address using a regex in JavaScript?

2 Answers2