textarea-maxlength.js

$(document).on("keypress", 'textarea[maxlength]', function(event){
  var ignore = [8,9,13,33,34,35,36,37,38,39,40,46],
  $this = $(this),
  maxlength = $this.attr('maxlength'),
  code = $.data(this, 'keycode')
  // check if maxlength has a value.
  // The value must be greater than 0
  if (maxlength && maxlength > 0) {
    // continue with this keystroke if maxlength
    // not reached or one of the ignored keys were pressed.
    return ( $this.val().length < maxlength
    || $.inArray(code, ignore) !== -1 )
  }
})
$(document).on("paste", 'textarea[maxlength]', function() {
  var $this = $(this),
  maxlength = $this.attr('maxlength')
  setTimeout(function () {
    $this.val($this.val().substr(0,maxlength))
  }, 100)
})

Return False will completely disable the textarea box, you cannot interact with it , That's will force the user to refresh the page if he want to edit the box for changes .