JavaScript test RegEx always returning false

Question

I'm trying to verify if a string looks like a valid e-mail address, however the function is always returning false regardless of what I type

function looksLikeMail(str) {
      var patt = new RegExp(/^(([^<>()\[\]\.,;:\s@\"]+(\.[^<>()\[\]\.,;:\s@\"]+)*)|(\".+\"))@(([^<>()[\]\.,;:\s@\"]+\.)+[^<>()[\]\.,;:\s@\"]{2,})$/i);
      return patt.test(str);
    }

var c1;
var c2;
var error = false;
c1 = document.getElementById("t8").value;
c2 = document.getElementById("t9").value;
if (document.getElementById("t8").value != "" || document.getElementById("t9").value != ""){
     if (document.getElementById("t8").value != ""){
     var validE;
     validE = looksLikeMail((String)(t8));
     if (!validE){
        error = true;
        alert("invalid email address");
       }
}

HTML

<div class="form-row">
  <label class="col align-self-center">&nbsp;<b>email (at least one)</b></label>
  </div>


  <div class="form-row">
  <div class="col-md-6 offset-md-3">
  <label for="inputEmail4">email-1</label>
  <input type="email" class="form-control" id="t8" placeholder="email">
  </div>

  <div class="col-md-6 offset-md-3">
  <label for="inputEmail5">email-2</label>
  <input type="email" class="form-control" id="t9" placeholder="email">
  </div>
  </div>

Seems to work for me: https://codepen.io/anon/pen/bJzwOR?editors=1111 What valid email address do you have problems with? — Constantin Groß, Apr 26 '19 at 15:47
Use *either* the RegExp constructor *or* regexp literal syntax. — Pointy, Apr 26 '19 at 15:51
Why do you assign the variables `c1` and `c2`, but then not use them? — Barmar, Apr 26 '19 at 15:58

score 1 · Answer 1 · answered Apr 26 '19 at 15:49

Your looksLikeMail is fine (returns true for 'a@a.com').

The rest of your JS though seems problematic. For one, your variable t8 is never defined. Also, (String) is invalid syntax. To cast in JS, you could do String(t8) instead. That being said, this is unnecessary because input.value will return a string anyways.

Since you seem unfamiliar with JS, i've done some small cleanup as well:

let t8 = document.getElementById("t8").value;
if (t8) {
     let validE = looksLikeMail(t8);
     if (!validE){
        error = true;
        alert("invalid email address");
     }
}

Rolly · Answer 2 · 2019-04-26T15:59:36.487

0

Try this code

        function looksLikeMail(str){
            var regex = /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
            return regex.test(str);
        }

        looksLikeMail("aa@aa.cc");// true
        looksLikeMail("aa@aa.c");// false
        looksLikeMail("demo_a-su@abcca.cd.bc");// true

Also you can test the regex here

https://regex101.com/r/777dwJ/1

Regex credits to. https://stackoverflow.com/a/46181/5708097

edited Apr 26 '19 at 15:59

answered Apr 26 '19 at 15:56

Rolly

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You should explain what you changed and how it solves the problem. – Barmar Apr 26 '19 at 15:57
well, basically im using another regex pattern – Rolly Apr 26 '19 at 16:01
Don't make this a challenge to find the difference. Explain what's wrong with his pattern. – Barmar Apr 26 '19 at 16:06

JavaScript test RegEx always returning false

2 Answers2