一道頗有意思的面試題

實現下面這道題中的machine函數

function machine() {
    
}
machine('ygy').execute() 
// start ygy
machine('ygy').do('eat').execute(); 
// start ygy
// ygy eat
machine('ygy').wait(5).do('eat').execute();
// start ygy
// wait 5s（這裏等待了5s）
// ygy eat
machine('ygy').waitFirst(5).do('eat').execute();
// wait 5s
// start ygy
// ygy eat

原型寫法

維護一個數組，異步就push函數，不是異步就push字符串

function machine(name) {
    if(!(this instanceof machine)){
        return new machine(name)
    }  
    this.name = name
    this.logs = []
    this.logs.push(`start ${name}`)
}
machine.defer = function(time){
    const times = time
    return function(){
        console.log(`wait ${times}s`)
          return new Promise((resolve)=>{
            setTimeout(()=>{resolve()},times*1000)
        })
    }
}
machine.prototype.execute = async function(){
    const logs = this.logs
    if(logs.length > 0){
         for(let i=0; i<logs.length; i++){
             if(typeof(logs[i]) === 'function'){
                 await logs[i]()
             }else {
                 console.log(logs[i])
             }
         }
     }
};
machine.prototype.do = function(argument){
    this.logs.push(`${this.name} ${argument}s`)
    return this
};

machine.prototype.wait = function(item){
    this.logs.push(machine.defer(item))
    return this
};

machine.prototype.waitFirst = function(item){
    this.logs.unshift(machine.defer(item))
    return this
};

es6寫法

維護一個queue隊列數組，裏面所有是構造函數，第一個參數代碼是否異步，第二個是callback

function machine(name) {
    return new Action(name)
}


const defer = (time, callback) => {
    return new Promise((resolve) => {
        setTimeout(() => {
            resolve(callback())
        }, time * 1000)
    })
}
class QueueItem {
    constructor(defer, callback) {
        this.defer = defer;
        this.callback = callback;
    }
}
class Action {
    queue = []
    constructor(name) {
        this.name = name;
        this.queue.push(new QueueItem(0, () => console.log(`start ${this.name}`)))
    }
    do(eat) {
        this.queue.push(new QueueItem(0, () => console.log(`${this.name} ${eat}`)))
        return this;
    }
    wait(time) {
        this.queue.push(new QueueItem(time, () => console.log(`wait ${time}s`)))
        return this;
    }
    waitFirst(time) {
        this.queue.unshift(new QueueItem(time, () => console.log(`wait ${time}s`)))
        return this;
    }
    async execute() {
        while(this.queue.length > 0) {
            const curItem = this.queue.shift();
            if (!curItem.defer) {
                curItem.callback();
                continue;
            }
            await defer(curItem.defer, curItem.callback)
        }
    }
}

比較

數組每個都是構造函數有點浪費空間