Активная кнопка html5

var text = document.getElementById('input-text'); 
var button = document.getElementById('input-button'); 
 
text.addEventListener('input', handle); 
text.addEventListener('keyup', handle); 
 
function handle(e) { 
  if (text.value.length >= 5) { 
    button.disabled = false; 
  } 
  if (e.keyCode === 8 || e.keyCode === 46) { 
    if (text.value.length <= 5) { 
      button.disabled = true; 
    } 
  } 
}

<form> 
<input id="input-text" type="text"> 
<input id="input-button" type="submit" disabled> 
</form>