ASP.NET character count of text box different than server side text box character count

I have a javascript function to display the remaining character count to the user on the page.
When I validate the length server side prior to a database insert to make sure it is not greater than the column length I'm actually getting a different count.

Researching online it appears that javascript counts new lines / CR and maybe some other special characters differently than C# does.

Does anyone have a workaround for this?

This is my javascript on the client side:

 <script>
        var textarea = document.getElementById('TxtComment');

        window.onload = textareaLengthCheck();

        function textareaLengthCheck() {
            var maxChars = 4000;
            var textArea = textarea.value.length;
            var charactersLeft = maxChars - textArea;
            var count = document.getElementById('cmt-characters-left');
            count.innerHTML = "Characters left: " + charactersLeft + " of " + maxChars;
        }

        textarea.addEventListener('keyup', textareaLengthCheck, false);
        textarea.addEventListener('keydown', textareaLengthCheck, false);

    </script>

Tried adding this - but it seemed to make the problem even worse:

 var textArea = textarea.value.replace(/(\r\n|\n|\r)/g, "").length;

I figured it out.
Javascrit was counting the "\r\n" as 1 character, C# was counting as 2 characters.
On the server side C# validation I changed it to this:

TxtComment.Text = this.TxtComment.Text.Replace("\r\n", "\n");
if (this.TxtComment.Text.Trim().Length > 4000)
{
    ... your Validation message here ...
}