fckeditor对输入内容实体长度的判断

//fckEditor 内容长度
        function GetLength(str){
            var oEditor = FCKeditorAPI.GetInstance(str) ; 
            var checkContent= oEditor.EditorDocument ; 
            var contentLength ; 
            if ( document.all ){
                contentLength= checkContent.body.innerText.trim().length ; 
            } else{
                var r = checkContent.createRange() ; 
                r.selectNodeContents( checkContent.body ) ; 
                contentLength= r.toString().trim().length ; 
            }
            return contentLength; 
        } 
        //去掉字符串的空格 
        String.prototype.trim = function() { 
            return $.trim(this.replace(/(^[s]*)|([s]*$)/g, "")); 
        } 

var content = FCKeditorAPI.GetInstance("replyPosts").GetHTML();
            if(content.length == 0 || GetLength("replyPosts") == 0){
                showTip("发表不能为空",1,"info");
                return false;
            }