Validate textarea in html with java script

Question

I'm trying to prevent users from inputting and submitting single quotes ( ' ) into the textarea. below is what I have, but it isn't work.

    <script>
    function valtxtarea() {
        var val = document.getElementById('textarea').value;

        if ('\''.test(val)) {
            alert('do not add single qoutes to your inputs!');
        }
    }

</script>

<form>
    enter text below
    <textarea>input contents here</textarea>
    <input type="button" onclick="valtxtarea();" value="send">
</form>

.test is for regular expressions what you have is a string, did you mean to do /'/.test(val). You should have been getting a .test is not a function or similar error on your browser's developer tools console — Patrick Evans
– Patrick Evans, Commented Jan 29, 2016 at 12:43

Vicky Gonsalves · Accepted Answer · 2016-01-29 12:46:30Z

3

You missed the id attribute as well as the regex isn't valid

function valtxtarea() {
  var val = document.getElementById('textarea').value;

  if (/\'/.test(val)) {
    alert('do not add single qoutes to your inputs!');
  }
}

<form>
  enter text below
  <textarea id="textarea"></textarea>
  <input type="button" onclick="valtxtarea();" value="send">
</form>

answered Jan 29, 2016 at 12:46

Vicky Gonsalves

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2 Comments

Kojo Amakye Over a year ago

How do I add other characters like ),(,%. A link to a tutorial if any will be fine.

Vicky Gonsalves Over a year ago

u need to check regex tutorials

Michael Hobbs · Accepted Answer · 2016-01-29 13:04:04Z

Better yet, why not prevent them from even typing it?

  <form>
  enter text below
  <textarea id='inputText' oninput="valtxtarea();"></textarea>
  <input type="button" value="send">
  </form>

  <script>
  var oldValue = "input contents here";
  document.getElementById('inputText').value = oldValue;
  function valtxtarea() {
    var textArea = document.getElementById('inputText');
    if (textArea.value.match(/.*\'.*/g)) {
        textArea.value = oldValue;
    } else {
      oldValue = textArea.value;
    }
  }
  </script>

With this every time they type a char it is check and if it contains a ' then it sets it back to the old value. You could easily expand it to include other characters you do not want to allow.

Stian · Accepted Answer · 2016-01-29 12:42:27Z

0

var val = document.getElementById('textarea').value;

There is no HTML element with the id textarea.

Do something like this:

<textarea id="textarea">input contents here</textarea>

Also you probably want to prevent form submission if there is a validation error, so put return false; in the if in valtxtarea() and put return valtxtarea() in the onclick.

answered Jan 29, 2016 at 12:42

Stian

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