Steps to develop a countdown timer for every iteration of sending an API request using a specified list

Question

Steps to develop a countdown timer for every iteration of sending an API request using a specified list

Recently, I encountered a challenge with my JavaScript array that holds 40 items. My goal was to develop a function capable of cycling through each item in the array and initiating an API call based on the current value.

The caveat here is that I needed a 3-second interval between each API call to avoid surpassing the allowable limit of API calls per second.

In my attempt to resolve this issue, I created the following function to fetch a list of properties stored in an array:

const getPropertiesInCity = (properties) => {
  for(i = 0; i < properties.length; i++){
    let property = properties[i]
    setTimeout(() => {
      getPropertyDetails(property.zpid)
    }, 5000)
  }
}

The outcome of running this function resulted in a series of errors followed by successful responses, as indicated below:

Error
Error
Error
...
Have the property
Have the property
Have the property

The errors were a direct result of exceeding the specified time frame for sending requests. The function would pause for 5 seconds before producing all the errors at once, followed by 3 positive responses.

javascript express settimeout

Answer 1

Answer №1

Your approach to scheduling API calls all at once within a 5-second time frame may not effectively space them out as intended. This is because `setTimeout()` function allows for non-blocking execution, causing the entire loop to run immediately without intervals between calls. To address this issue and achieve a delay of 3 seconds between each call, you can adjust the timer value within the loop iteration.

const getPropertiesInCity = (properties) => {
  for(let i = 0; i < properties.length; i++){
    let property = properties[i]
    setTimeout(() => {
      getPropertyDetails(property.zpid)
    }, i * 3000)
  }
}

An alternative technique involves initiating the subsequent iteration with a set timeout duration directly within the loop:

const getPropertiesInCity - (properties) => {
    let i = 0;
    function run() {
        if (i < properties.length) {
            getPropertiesDetails(properties[i++].zpid);
            // schedule next iteration of the loop
            setTimeout(run, 3000);
        }
    }
    run();
};

In scenarios where `getPropertiesDetails()` either returns a promise or requires a completion callback, an effective strategy would be to commence the following iteration after its execution by incorporating a timer for a delayed start rather than triggering it immediately upon invocation.

Answer 2

Your approach to scheduling API calls all at once within a 5-second time frame may not effectively space them out as intended. This is because `setTimeout()` function allows for non-blocking execution, causing the entire loop to run immediately without intervals between calls. To address this issue and achieve a delay of 3 seconds between each call, you can adjust the timer value within the loop iteration.

const getPropertiesInCity = (properties) => {
  for(let i = 0; i < properties.length; i++){
    let property = properties[i]
    setTimeout(() => {
      getPropertyDetails(property.zpid)
    }, i * 3000)
  }
}

An alternative technique involves initiating the subsequent iteration with a set timeout duration directly within the loop:

const getPropertiesInCity - (properties) => {
    let i = 0;
    function run() {
        if (i < properties.length) {
            getPropertiesDetails(properties[i++].zpid);
            // schedule next iteration of the loop
            setTimeout(run, 3000);
        }
    }
    run();
};

In scenarios where `getPropertiesDetails()` either returns a promise or requires a completion callback, an effective strategy would be to commence the following iteration after its execution by incorporating a timer for a delayed start rather than triggering it immediately upon invocation.

Answer 3

Answer №2

If you're looking to leverage the power of the iter-ops library (which I happen to have authored), here's a sample code snippet for you:

import {pipeAsync, map, wait, delay} from 'iter-ops';

const properties = [...]; // your list of objects

const i = pipeAsync(
    properties,
    map(p => getPropertyDetails(p.zpid)), // transforming into requests
    wait(), // waiting for request completion
    delay(5000) // adding a 5-second delay
); //=> AsyncIterable

// handling any errors during iteration:
i.catch(err => {
    console.log('CAUGHT:', err);
});

(async function () {
    for await (const a of i) {
        console.log(a); // outputting the results of getPropertyDetails
    }
})();

This example not only provides you with the outcomes of each getPropertyDetails call but also centralizes error management.

Answer 4

If you're looking to leverage the power of the iter-ops library (which I happen to have authored), here's a sample code snippet for you:

import {pipeAsync, map, wait, delay} from 'iter-ops';

const properties = [...]; // your list of objects

const i = pipeAsync(
    properties,
    map(p => getPropertyDetails(p.zpid)), // transforming into requests
    wait(), // waiting for request completion
    delay(5000) // adding a 5-second delay
); //=> AsyncIterable

// handling any errors during iteration:
i.catch(err => {
    console.log('CAUGHT:', err);
});

(async function () {
    for await (const a of i) {
        console.log(a); // outputting the results of getPropertyDetails
    }
})();

This example not only provides you with the outcomes of each getPropertyDetails call but also centralizes error management.

Steps to develop a countdown timer for every iteration of sending an API request using a specified list

Answer №1

Answer №2

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