正则 过滤敏感字

<script>
window.onload = function(){

var oTxt1 = document.getElementById("txt1");
var oTxt2 = document.getElementById("txt2");
var oBtn = document.getElementById("btn");

oBtn.onclick = function(){
var reg = /北京|淘宝|百度/g;

oTxt2.value = oTxt1.value.replace(reg,'***');
}
}
</script>

<textarea id="txt1" name="" rows="" cols=""></textarea><br />
<input id="btn" type="button" value="过滤" /><br />
<textarea id="txt2" name="" rows="" cols=""></textarea>