我有一堂課，另一堂課延伸了第一堂課。在我的代碼中，我創建了擴展類的一個新實體：new MyCustomEndpoint(router);

問題handleIsNotOk是undefined在initMyRoutes

export class MyEndpoint {
    constructor(router: express.Router) {
        this.initMyRoutes(router); 
    }

    protected initMyRoutes(router: express.Router) {
        router.get(`/v1/isok`, this.handleIsOk);
    }

    protected handleIsOk = (req: express.Request, res: express.Response) => {
        res.send(200);
    }
}


export class MyCustomEndpoint extends MyEndpoint{
    private test = "Test";

    protected initMyRoutes(router: express.Router) {
        console.log(this.handleIsNotOk); // undefined
        console.log(this.handleIsNotOkFn);

        router.get(`/v1/isokcustom`, this.handleOk); // this works
        router.get(`/v1/isnotok`,this.handleIsNotOk); // this doesn't works
        router.get(`/v1/isnotokfn`, this.handleIsNotOkFn); // this doesn't works
        router.get(`/v1/isnotokfn`, (req, res)this.handleIsNotOkFn(req,res)); // works but it's ugly since it's different compared to router.get(`/v1/isokcustom`, this.handleOk);
    }

    protected handleIsNotOk = (req: express.Request, res: express.Response) => {
        res.send(200);
    }

    protected handleIsNotOkFn(req: express.Request, res: express.Response){
        console.log(this.test); // undefined
        res.send(200);
    }
}

...

new MyCustomEndpoint(router);

為什么會這樣？undefined在我看來不應該

uj5u.com熱心網友回復：

我敢打賭這就是原因

router.get(`/v1/isnotokfn`, this.handleIsNotOkFn);

如果你將它系結到實體，它會作業得很好：

router.get(`/v1/isnotokfn`, this.handleIsNotOkFn.bind(this));

uj5u.com熱心網友回復：

自我回答

感謝@mbojko @Keith @VLAZ 和其他所有人的答案。

即使技術上正確，解決方案也不符合我的需求。我的用例有點奇怪，我這樣做是有原因的。

僅供參考：這是適合我需求的解決方案

export class MyCustomEndpoint extends MyEndpoint{

    constructor(router: express.Router) {
        super(router);
        this.initCustomRoutes(router);
    }

    // will be called in the constructor of the super class
    protected initMyRoutes(router: express.Router) {
        router.get(`/v1/isokcustom`, this.handleOk); 
    }

    private initCustomRoutes(router: express.Router) {
        router.get(`/v1/isokcustom`, this.handleOkCustom); 
    }

    protected handleOkCustom = (req: express.Request, res: express.Response) => {
        res.send(200);
    }

}

uj5u.com熱心網友回復：

您覆寫initMyRoutes并且您正在等待您的母親類呼叫 new initMyRoutes。你應該MyCustomEndPoint在你呼叫的地方有一個建構式initMyRoutes。MyCustomEndPoint從不打電話initMyRoutes

轉載請註明出處，本文鏈接：https://www.uj5u.com/net/488170.html

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擴展類中未定義箭頭函式

自我回答