解决firefox不支持innerText的办法

js代码：
<script>
window.onload = function(){

if(window.navigator.userAgent.toLowerCase().indexOf("msie")==0){ //firefox innerText
   HTMLElement.prototype.__defineGetter__(     "innerText",
    function(){
     var anyString = "";
     var childS = this.childNodes;
     for(var i=0; i<childS.length; i++) {
      if(childS[i].nodeType==1)
       anyString += childS[i].tagName=="BR" ? '\n' : childS[i].textContent;
      else if(childS[i].nodeType==3)
       anyString += childS[i].nodeValue;
     }
     return anyString;
    }
   );
   HTMLElement.prototype.__defineSetter__(     "innerText",
    function(sText){
     this.textContent=sText;
    }
   );
};

var test = document.getElementById("test");
var innerText_s = test.innerText;
if( innerText_s == undefined ){
alert( test.textContent ); // firefox
}else{ 
alert( test.innerText);
};


}


</script>

html代码

<div id="test">
      <span style="color:red">test1</span> test2
</div>