Generator非同步處理

{
    // genertaor基本定義,next()一步步執行
    let tell=function* (){
        yield 'a';
        yield 'b';
        return 'c'
    };
    let k=tell();

    console.log(k.next()); //{value: "a", done: false}
    console.log(k.next()); //{value: "b", done: false}
    console.log(k.next()); //{value: "c", done: true}
 

    console.log(k.next());//{value: undefined, done: true}

}

應用場景

// 應用場景，變數變化的實時儲存
{
    let draw=function(count){
        // 具體抽獎邏輯
        console.info(`剩餘${count}次`)
    }

    let residue=function *(count){
        while(count>0){
            count--;
            yield draw(count);
        }
    }

    let star
 
=residue(5);
    let btn=document.createElement("button");
    btn.id='star';
    btn.textContent='抽獎';
    document.body.appendChild(btn);
    document.getElementById('star').addEventListener("click",function(){
        star.next();
    },false)
}

長輪詢(服務端某個狀態在變化，我們也需要實時去訪問變化)

{
    // 長輪詢(服務端某個狀態在變化，我們也需要實時去訪問變化)
 

    let ajax=function* (){
        yield new Promise(function(resolve,reject){
            setTimeout(function(){
                resolve({code:1})
            },200);
        })
    }

    let pull=function(){
        let genertaor=ajax();
        let step=genertaor.next();
        step.value.then(function(d){
            if(d.code!=0){
                setTimeout(function(){
                    console.info('wait');
                    pull()
                },1000);
            }else {
                console.log(d);
            }
        })
    }

    pull();
}

Decorator函式修飾符，通過修飾器修改類的行為