How to detect new empty line in textarea with Javascript?

Question

I would like to detect a new empty line in a text area and if the user just pressed enter in the text area, without entering any data to return false and echo a message. I have made some research and thought of something like this:

var validatef ....
var code = (e.keyCode ? e.keyCode : e.which);
if (validatef == 'a value here' || code == 13) { 
  somevarhere.textcontent = 'Message';
  return false;
}
else {....}

But it doesn't seem to work.

@bksi I mean that when the user hits enter without entering any data, it doesn't do anything. — Adrian, Oct 25 '13 at 20:48
New empty line and pressed enter? What about just detect two consecutive pressed enters? — , Oct 25 '13 at 20:48
@Adrian, Add +1 to some counter variable on enter pressed and -1 on any other key. On any key pressed check if counter > 2 and do your stuff. — , Oct 25 '13 at 20:49
I'm not sure if we get keyCode onSubmit. I think you are looking for onkeydown — Akshaya Shanbhogue, Oct 25 '13 at 20:54

score 2 · Answer 1 · edited May 23 '17 at 12:28

2

You can detect an empty line in a textarea by checking for the values:

\r\n (works fine for me) or \n

Just replace the text a value here with \r\n or \n what best suits you.

EDIT:

Check How to count string occurrence in string? to count regex appearances. So you can make a for loop to show the error message on /\s/g.

Hope it helps.

edited May 23 '17 at 12:28

Community

1
1

answered Oct 25 '13 at 20:51

Diosney

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1

\r\n? Isn't it just \n now? – bjb568 Oct 25 '13 at 20:53
Well, \r\n works like a charm for me in the latest browsers :) – Diosney Oct 25 '13 at 20:55
Dude is right, it works only with \n. But the problem is that i want it to show the error foreach space or for 100 spaces. It works for the first enter, after doesn't – Adrian Oct 25 '13 at 20:58
Well, do a global regex test then. Something like `/\n/g.test(value)` – Diosney Oct 25 '13 at 21:01
Test page: http://jsfiddle.net/gUBCL/ It only works in chrome. Tested in Nightly webkit, FF, chrome, and opera. – bjb568 Oct 25 '13 at 21:03
@Adrian: Sorry, the link is this one: http://stackoverflow.com/questions/4009756/how-to-count-string-occurrence-in-string – Diosney Oct 25 '13 at 21:13

score 1 · Answer 2 · answered Oct 25 '13 at 20:56

1

just test if the user pressed enter twice

/\n\n/.test(this.value)

answered Oct 25 '13 at 20:56

Jay Harris

4,201
17
21

score 1 · Accepted Answer · answered Oct 25 '13 at 21:02

1

Try this

 $('textarea').on('keypress', function(e) {
    var val = $('textarea').val();
    if (e.which == 13) {
if(! /\S/.test(val)) {
   alert("no data");
}
    }
});

this alerts no data for each keypress.

This is in jQuery but it will be similar even in plain Javascript

Here is the demo http://jsfiddle.net/TUCx8/

answered Oct 25 '13 at 21:02

Kishore

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1
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Would have been great if it was javascript don;t know how $('textarea').on('keypress', function(e) translates to javascript – Adrian Oct 25 '13 at 21:23

score 1 · Answer 4 · answered Oct 25 '13 at 21:04

According to the first sentence of the question, this may be one of possible solutions:

var enters = 0;
$('textarea').keypress(function(event) {
    if (event.which == 13)
        enters++;
    else
        enters = 0;
    if (enters > 1) {
        alert('You hit 2 new lines!');
    }
});

Live example http://jsfiddle.net/fp6xk/

score 0 · Answer 5 · answered Oct 25 '13 at 21:27

Another one solution is to check an empty line right before the end of text:

(function(){
    $('textarea').keyup(function(event) {
        if (/(\r?\n){2}$/.test($(this).val())) {
            alert('2 consecutive empty lines at the end!');
        }
    });
})();

It would work independent of consecutive enter presses. http://jsfiddle.net/fp6xk/4/

How to detect new empty line in textarea with Javascript?

5 Answers5