实现一个lazyMan

LazyMan("gary"); 
//Hi this is gary!
LazyMan("gary").sleep(3).eat("dinner");
// Hi this is gary!
// Wake up after 3s!
// Eat dinner !
LazyMan("gary").sleepFirst(2).eat("dinner");
// Hi this is gary!
// Eat dinner !
// Wake up after 2s!
LazyMan("gary").sleep(2).eat("supper").sleep(1).eat("dinner")
// Hi this is gary!
// Wake up after 2s!
// Eat supper !
// Wake up after 1s!
// Eat dinner !

function $LazyMan(name) {
    this.tasks = [];
    var _this = this;
    var fun = (function(n) {
        var name = n;
        return function() {
            console.log(`Hi this is ${name}!`);
            _this.next();
        }
    })(name);
    this.tasks.push(fun); //把事件加入到队列中
    setTimeout(function() {
        _this.next(); //下次eventLoop 启动任务
    }, 0);
}

$LazyMan.prototype.next = function() {
    var fn = this.tasks.shift(); //获取当前队列中第一个并且删除队列中第一个
    fn && fn(); //执行
};

$LazyMan.prototype.eat = function(food) {
    var _this = this;
    var fun = (function(food) {
        return function() {
            console.log(`Eat ${food} !`);
            _this.next();
        }
    })(food);
    this.tasks.push(fun);
    return this; //链式调用
};

$LazyMan.prototype.sleep = function(time) { //单位秒
    var _this = this;
    var fun = (function(time) {
        return function() {
            setTimeout(function() {
                console.log(`Wake up after ${time}s!`);
                _this.next();
            }, time * 1000);
        }
    })(time);
    this.tasks.push(fun);
    return this;
};

$LazyMan.prototype.sleepFirst = function(time) {
    var _this = this;
    var fun = (function(time) {
        return function() {
            setTimeout(function() {
                console.log(`Wake up after ${time}s!`);
            }, time * 1000);
            _this.next();
        }
    })(time);
    this.tasks.unshift(fun); //推入
    return this;
};

function LazyMan(name) {  //封装
    return new $LazyMan(name);
}

LazyMan("gary"); 
//Hi this is gary!
LazyMan("gary").sleep(3).eat("dinner");
// Hi this is gary!
// Wake up after 3s!
// Eat dinner !
LazyMan("gary").sleepFirst(2).eat("dinner");
// Hi this is gary!
// Eat dinner !
// Wake up after 2s!
LazyMan("gary").sleep(2).eat("supper").sleep(1).eat("dinner")
// Hi this is gary!
// Wake up after 2s!
// Eat supper !
// Wake up after 1s!
// Eat dinner !