How Can I Prevent Excessive API Requests When Using Async/Await in JavaScript?

Combining Async Functions, Await, and setTimeout

Utilizing the latest JavaScript async features, this guide provides a solution to a common performance issue: sending excessive requests to Google APIs in a short timeframe. The goal is to introduce a sleep function to delay requests and enhance script performance.

Original Code:

This initial code employs the async/await pattern efficiently:

async function asyncGenerator() {
    while (goOn) {
        var fileList = await listFiles(nextPageToken);
        var parents = await requestParents(fileList);
    }
}

Problem:

The code executes the while loop too rapidly, resulting in a deluge of requests to the Google API.

Attempted Solution:

To address this, a sleep function was created:

async function sleep(fn, par) {
    return await setTimeout(async function() {
        await fn(par);
    }, 3000, fn, par);
}

However, this function fails to return the request response properly.

Correct Implementation:

The issue with the sleep function lies in the lack of a promise returned by setTimeout. To resolve this, a promisified version can be created:

function timeout(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
}
async function sleep(fn, ...args) {
    await timeout(3000);
    return fn(...args);
}

Optimized Loop:

To slow down the loop execution, a sleep function that pauses the entire computation is not optimal. A better approach is to use a Promise.all construct that includes the sleep function:

while (goOn) {
    var [parents] = await Promise.all([
        listFiles(nextPageToken).then(requestParents),
        timeout(5000)
    ]);
}

This modification ensures that the computation of parents takes a minimum of 5 seconds, effectively slowing down the loop and preventing excessive API requests.

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