NodeJS：通过 API 发出更少的请求

Question

I am trying to process response data and do not make next request before current data didn't processed. I tried use async/await and generators.

Generator:

    private *readData() {
        const currentUrl = this.getUrl();
        const requestSettings = this.getRequestSettings();
        yield axios.get( currentUrl, requestSettings).then( (response: any) => {
            console.log('Make request');
            return this.getData(response);
        });
    }

    *readItem() {
        let responseData: any;

        if (!responseData) {
            const response = this.readData();
            responseData = response.next();
        }
        console.log('res data:', responseData['value']);
        yield responseData['value'].then((res: any) => {
            return res;
        });
     }

and then in the main code I do next:

for (let i=0;i<10;i++) {
    item = transport.readItem().next();
    console.log("R:", item);
}

Another idea was using async/await

async readItems() {
    const headers = this.settings.headers;
    const response = await axios.get( url, {
        headers: headers
    });
    return response.data;
}

But in this case I get a promise in the response, if I just try to call this method 10 times.

I read 10 items, but I still make 10 requests to the server. Is it possible make one request, processed 10 items, and then make the second request? Maybe I have to use another pattern or whatever.

Answer 1

Async/await is right approach, just put await in front of readItem() and the Promise you get will be await ed that will give you desired. If your loop is in top level use readItem().then() . The latest NodeJS version allows await in top level.

for (let i=0;i<10;i++) {
    item = await transport.readItem();
    console.log("R:", item);
}

Answer 2

I found next solution

(async () => {
    for (let i = 0; i < 10; i++) {
        item = await transport.readItem();
        console.log("R:", item);
    }
})();

because I ran this part of code inside script without any functions/methods