Checking the input if its empty

Question

I am pretty new to jQuery so I have a problem with this. I am trying to check if input is empty by jQuery. I have this script:

$('#submit').click(function(){
  if($.trim($('#username').val()) == ''){
    alert('Input can not be left blank');
  }
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input name="username" id="username" type="text" placeholder="Enter your Username"/>
<button class="btn btn-info btn-block login" name="submit" id="submit" type="submit">Create an Account</button>

Thanks for reply.

What's your actual question? "How should I best check if a string is empty in Javascript"? https://stackoverflow.com/questions/154059/how-do-you-check-for-an-empty-string-in-javascript — wally, Nov 06 '17 at 17:08
My problem is that if I click the button the alert doesnt show up. — Adam Šulc, Nov 06 '17 at 17:14
You can see from the snippet in your question that this works fine. If you have issues with it I'd suggest you check the console for errors — Rory McCrossan, Nov 06 '17 at 17:14
Or it's possible that you did the thing with your browser to suppress alerts. You should try it using console.log instead. — Taplar, Nov 06 '17 at 17:15
It is working fine for me. Have you added the validation script before jQuery file? — Hanif, Nov 06 '17 at 17:22
The snippet here works for me as well. I have no idea why it doesnt work on my site. — Adam Šulc, Nov 06 '17 at 17:26
You could search a bit before asking this question, this has been answered here : https://stackoverflow.com/questions/154059/how-do-you-check-for-an-empty-string-in-javascript — Anand Singh, Feb 22 '18 at 10:44

Tony M · Accepted Answer · 2017-11-06T17:25:10.180

1

Check the length property to determine if it's empty:

if ($.trim($('#username').val()).length > 0) {
// not empty
}

Edit: Removed white spaces $.trim

edited Nov 06 '17 at 17:25

answered Nov 06 '17 at 17:09

Tony M

741
4
16

2

This doesn't account for whitespace only input, like the OP is removing with the trim. Edit: and you have an unclosed '(' in your code. – Taplar Nov 06 '17 at 17:13

Checking the input if its empty

1 Answers1