ext js findChild

最近做了一个程序模块，根据一棵树查找树节点，树的id是js自己生成的，所以我就选用其他方式来查找树节点
var node = TreePanel.root.findChild( String attribute, Mixed value ) ;
但是我调用了方法之后 火狐一直报错 node为null;
后来安装了spket之后 翻看源代码
findChild : function(attribute, value, deep){
        return this.findChildBy(function(){
            return this.attributes[attribute] == value;
        }, null, deep);
    },

    /**
     * Finds the first child by a custom function. The child matches if the function passed returns <code>true</code>.
     * @param {Function} fn A function which must return <code>true</code> if the passed Node is the required Node.
     * @param {Object} scope (optional) The scope (<code>this</code> reference) in which the function is executed. Defaults to the Node being tested.
     * @param {Boolean} deep (Optional) True to search through nodes deeper than the immediate children
     * @return {Node} The found child or null if none was found
     */
    findChildBy : function(fn, scope, deep){
        var cs = this.childNodes,
            len = cs.length,
            i = 0,
            n,
            res;
        for(; i < len; i++){
            n = cs[i];
            if(fn.call(scope || n, n) === true){
                return n;
            }else if (deep){
                res = n.findChildBy(fn, scope, deep);
                if(res != null){
                    return res;
                }
            }
           
        }
        return null;
    },



////////////////////////////////////////////////
findChild : function(attribute, value, deep){

原来还隐含了一个参数deep ，默认为false 只查找到他的子节点，
把他设为true 可以查找到root下的所有子孙节点。
findChild('pid',123,true);

总结：API要尽量与自己用的开发版本相匹配，ext中还有很多函数可用却在api之中找不到，希望大家能够互相分享下。