db.User.findOne({}).exec()

var data = [
    { userId: 8, title: 'title1' },
    { userId: 11, title: 'other' },
    { userId: 15, title: null },
    { userId: 19, title: 'title2' }
];

var find = function(origin){
    //your code are here...
}

//查找data中，符合条件的数据，并进行排序
var result = find(data).where({"title": /\d$/}).orderBy('userId', 'desc');
console.log(result);        
// 返回值
// [{ userId: 19, title: 'title2'}, { userId: 8, title: 'title1' }];

var find = function(data) {
    function A(data) {
        this.$data = [];
        var $this=this;
        this.where = function(where) {
            data.forEach(function(e) {
                for (var key in where) {
                    if (where[key] instanceof RegExp) {
                        if (where[key].test(e[key])) {
                            $this.$data.push(e);
                        }
                    } else if (where[key] == e[key]) {
                        $this.$data.push(e);
                    }
                }
            });
            return this;
        };
        this.orderBy=function(id,order){
            this.$data.sort(function(a,b){
                if(order="desc"){
                    return b[id]-a[id];
                }
            });
            return this.$data;
        }
    };
    return new A(data);
}
var result = find(data).where({ "title": /\d$/ }).orderBy('userId', 'desc');
console.log(result);
//[ { userId: 19, title: 'title2' },
// { userId: 8, title: 'title1' } ]

var m= new Map();
var o={
	a:1
};

m.set(o,"123");
m.get(o);  // "123"

m.has(o);  // true
m.delete(o); // true
m.has(o); // false

var xhr = new XMLHttpRequest();
//不考虑浏览器兼容性
xhr.open("get","garychang.cn",true);
xhr.onreadystatechange=function(){
	if(xhr.readyState==4){
		if(xhr.status>=200&&xhr.status<300||xhr.status==304){
			console.log(xhr.responseText);
		}
	}
}
//或者 onload方法稍稍简单点。
xhr.onerror=function(err){
	//error......
}
xhr.send(null);