[poorking]

Только цифры
<textarea id = "#txt"></textarea>

<script type = "text/javascript">
      var events = ["keydown", "keyup", "cut", "paste", "input", "change"];
	
	function digits(){
		this.value = this.value.replace(/[^\d]+/g, "");
	}
	
	var t = document.getElementById("#txt");
	for(var i = 0; i < events.length; i ++){
		t.addEventListener(events[i], digits, false);
	}
</script>