Text area validation?

I want to validate my text are while entering data.

I had written code for on keypress event.

function validateQuestionTextArea(questionid)
{

  var txtbx=$('questions-'+questionid).value;

  if(txtbx.开发者_开发技巧length > 99)
  {
    showValidationMessage('questionMaxLengthValidation');
    return false
  }

  return true

}

The problem with this is that I can use backspace or delete once it reached the 100.

Which event should I use?

you might wanna use KeyUp instead ^^

see jquery way similar question.. or follow below steps

first get the data then trim from both side then count and compare with max length