How to count number of character which is entered in textbox?

Question

I have a label lblCountCharacter with text "4000" and a textbox txtAddNote where users can enter text.

On entering one character in txtAddNote, the label text is decreased by one.

Please help me write a function for this in asp.net using C#.

Answer 1

In order to avoid post backs you can use jQuery to determine the length of the text in the text box:

var myLength = $("#myTextbox").val().length;

Answer 2

I think you can get a better solution to this by using just javascript/jQuery. Using c# is going to involve having to use AJAX to re-render the Label each time.

var characterLimit = 4000
var charLeft = characterLimit - $(".textbox").val().length
$(".label").html(charLeft);