实现一个lazyman

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请设计一个 LazyMan 类，实现以下功能。

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LazyMan('Tony');
// Hi I am Tony

LazyMan('Tony').sleep(10).eat('lunch');
// Hi I am Tony
// 等待了10秒...
// I am eating lunch

LazyMan('Tony').eat('lunch').sleep(10).eat('dinner');
// Hi I am Tony
// I am eating lunch
// 等待了10秒...
// I am eating diner

LazyMan('Tony').eat('lunch').eat('dinner').sleepFirst(5).sleep(10).eat('junk food');
// Hi I am Tony
// 等待了5秒...
// I am eating lunch
// I am eating dinner
// 等待了10秒...
// I am eating junk food

一、试题分析

LazyMan 类具有的特点有：

  • 无需new关键字便可创建对象。
  • 所有方法支持链式调用。
  • eat 方法并不是立即执行。

二、我的实现

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function LazyMan(name) {
    if (!(this instanceof LazyMan)) {
        return new LazyMan(name);
    }
    this.name = name;
    this.delayTime = 0;
    this.tasks = [];
    console.log(`Hi I am ${this.name}`);
    this._ready();
}

LazyMan.prototype._ready = function () {
    setTimeout(() => {
        setTimeout(() => {
            console.log(`等待了${this.delayTime}秒...`);
            this._doTasks();
        }, this.delayTime * 1000);
    }, 0);
}

LazyMan.prototype._doTasks = function () {
    const tasks = this.tasks;
    if (tasks.length === 0) return;
    const {delayTime, callback} = tasks[0];
    setTimeout(() => {
        callback && callback();
        tasks.shift();
        this._doTasks();
    }, delayTime);
}

LazyMan.prototype.eat = function (foods) {
    this.tasks.push({
        delayTime: 0,
        callback() {
            console.log(`I am eating ${foods}`);
        },
    });
    return this;
}

LazyMan.prototype.sleep = function (seconds) {
    if (seconds >= 0) {
        this.tasks.push({
            delayTime: seconds * 1000,
            callback() {
                console.log(`等待了${seconds}秒...`)
            }
        });
    }
    return this;
}

LazyMan.prototype.sleepFirst = function (seconds) {
    if (seconds > 0) {
        this.delayTime = seconds;
    }
    return this;
}

三、实现思路细节优化

  • eat、sleep、sleepFirst 均会向任务列表插入回调
  • 简化整个任务队列的执行
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function LazyMan(name) {
    if (!(this instanceof LazyMan)) {
        return new LazyMan(name);
    }
    this.name = name;
    this.tasks = [];
    console.log(`Hi I am ${this.name}`);
    // 让任务队列注册后自动执行
    setTimeout(() => {
        this.next();
    }, 0);
}

LazyMan.prototype.next = function () {
    const task = this.tasks.shift();
    task && task();
}

LazyMan.prototype.eat = function (foods) {
    this.tasks.push(() => {
        console.log(`I am eating ${foods}`);
        this.next();
    });
    return this;
}

LazyMan.prototype.sleep = function (seconds) {
    if (seconds >= 0) {
        this.tasks.push(() => {
            setTimeout(() => {
                console.log(`等待了${seconds}秒...`);
                this.next();
            }, seconds * 1000);
        });
    }
    return this;
}

LazyMan.prototype.sleepFirst = function (seconds) {
    if (seconds > 0) {
        this.tasks.unshift(() => {
            setTimeout(() => {
                console.log(`等待了${seconds}秒...`);
                this.next();
            }, seconds * 1000);
        });
    }
    return this;
}

四、相关讨论：

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