題目記錄

實現下面這道題中的machine 函式功能

function machine(){}

machine('ygy').execute()  // 輸出 start ygy 
machine('ygy').do('eat').execute // 輸出 start ygy ygy eat
machine('ygy').wait(5).do('eat').execute() // start ygy (wait 5s等了5s)  ygy eat
machine('ygy').waitFirst(5).do('eat').execute() // wait 5s  start ygy  ygy eat

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答案

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)
        }
    }
}
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