Limit the number of characters in the Asp.Net TextArea

This tips will help you to limit the number of characters in the Asp.Net TextArea or Asp.Net Multiline Textbox. It uses a JavaScript function to limit the characters keyed in the TextArea.

Step 1: Add the below JavaScrpit function between the in your aspx page.

function fnLimitTextAreaChars(textareaName, NoOfChars)
{
if (textareaName.value.length > NoOfChars)
{
textareaName.value = textareaName.value.substring(0, NoOfChars);
}
}

Step 2: In the code-behind at Page_Load event, add the two lines as follows.

TextBox1.Attributes.Add(”onKeyDown”, “fnLimitTextAreaChars(this, 150)”);
TextBox1.Attributes.Add(”onKeyUp”, “fnLimitTextAreaChars(this, 150)”);

It’s done. Now when you type any letters in the TextArea, it will allow only first 150 characters. The rest will be truncated. Try yourself.