[CrazzyBerg]

<input type="text" id="txtCommand">
<script>
	var blackList = ['go', 'nogo'];

	document.getElementById("txtCommand").onkeyup = function() {
	var expr = new RegExp(blackList.join('|'));
	if (this.value.search(expr) !== -1) {
	this.value = '';
	}
}
</script>