document.write(document.body.textContent);

<script language="javascript">
function isIE(){ //ie?
if (window.navigator.userAgent.toLowerCase().indexOf("msie")>=1)
    return true;
else
    return false;
}

if(!isIE()){ //firefox innerText define
    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].innerText;
                anyString += childS[i].innerText;
            else if(childS[i].nodeType==3)
                anyString += childS[i].nodeValue;
        }
        return anyString;
    }
    );
    HTMLElement.prototype.__defineSetter__("innerText",
    function(sText){
        this.textContent=sText;
    }
    );
}
</script>