How do I order multiple API responses according to which request was sent first? In javascript/nodejs

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Hi, I've been working on a project that I want to make better, I had this upgrade idea on it, And it's requesting multiple times from an API at a short time, Now the problem here is that, How can I order the responses according to which request was sent first? In-depth, My code here requests multiple times in a for loop:

JavaScript

var queue = [];

function Request(text) {

  console.log(text);
  async function Test(){
  await Api.request(); //This is an example and not a real API request function
  let result = Api.response //
  var URL = result.Object();
      queue.push(URL);  
      var I = queue.shift();
      console.log(I)
  }
  Test()
}

for (Something) { // Yet again and example here.
  
    setTimeout(function() {
      Request(text);
}, 2000);
}

This is my code that requests from an API multiple times according to the for loop rule, For this sake, I made it clear as an example and not real API functions etc...

Let's say that the rule for the for loop here makes it that the API returns 3 responses

Response1 // Took 1 second to respond
Response3 // Took 1.5 seconds to respond
Response2 // Took 2 seconds to respond

Notice that the responses are not ordered accordingly, And they're randomized, Since Response3 Could be faster than Response2 and the examples goes on....

Now of course, Each response depending on the API will sometimes get eariler/later than the others, Which makes the problem here and my question here is that:

How can I know that this response came earlier/later but belongs to the first request, And same goes to the 2 other requests.

Request1: Response 1 // Took 1 second to respond
Request2: Response 2 // Took 2 seconds to respond
Request3: Response 3 // Took 1.5 seconds to respond

It doesn't matter if the code have to wait for Response 2 to come before Response 3 even though Response 3 came before Response 2.

I hope this made any sense, I'm sorry for my bad English. Thanks in advance.

(EDIT): Since it's too hard to explain what I'm trying to achieve, I'll post an actual piece of my code here:

var text = "How's work this week? | It's been pretty good not going to lie. It has been a pretty decent day as well, I like how everything is going this week, |  I hope it get's better."
const API  = require('SomeApiWrapperLibrary.js');
var queue = [];
async function processText(text) {

    var Object1 = "Something"
    const Rw = new Api.Client({
        usernameOrEmail: "something",
        password: "somethingelse"
    });
    async function Test(){
      console.log(text);
    await Rw.start(); //required
    let result = await Rw.makeTTS(voice, text);
    var URL = result.Object();
        queue.push( text + " : " + URL);         // queue is now [URL]
        var I = queue.shift();
        console.log(I)
    }
    Test()
}


const prefix = ' | ';

const splitText = text.split(prefix);

async function Request(){

for (const text of splitText) {


 await processText(text).then(console.log('Done'))

  
}

}
Request()

What I have tried:

What I tried here is to number-ize the response that's being pushed to the queue as you can see here:

JavaScript

var queue = []; 

var Number = 0;

function Request(text) {

  console.log(text);
  async function Test(){
  await Api.request(); //This is an example and not a real API request function
  let result = Api.response //
  Number++
  var URL = result.Object();
      queue.push( "URL " + Number + URL);  
      var I = queue.shift();
      console.log(I)
  }
  Test()
}

for (Something) { // Yet again and example here.
  
    setTimeout(function() {
      Request(text);
}, 2000);
}

But that's totally wrong because the number here Will always be from 1 to 3, Even if let's say the 2nd response was meant to be the first one, It'll still be called 2, If that makes any sense.

Posted 5-Jan-23 9:10am

ftk789

Updated 6-Jan-23 0:48am

v6

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2 solutions

Solution 1

You don't. API requests can vary in the length of time they take to process and return a result. Every request is handled independently from all others, and none of them have any idea the others even exist.

If you want the results returned in the same order the requests were made, you'd have to make the requests, one at a time, and wait for each to return before making the next request.

Posted 5-Jan-23 14:29pm

Dave Kreskowiak

Updated 5-Jan-23 14:32pm

v2

Comments

ftk789 6-Jan-23 0:41am

Thank you for your reply, I didn't think it's impossible to actually do such a thing, The idea looked pretty simple, But it seems that you have to wait for the first response then request the other, Which is slow for a fast app/program/project, But it's better than nothing, Thank you soo much for your reply man, I hope you have a great rest of your day!

Richard Deeming 6-Jan-23 5:50am

You don't have to wait for the first request to complete before you start the second; you just have to wait for the first request to complete before you process the second.

ftk789 6-Jan-23 6:04am

True, Now my question changes honestly, I need somehow to request from that for loop. But then somehow pause the for loop until the response comes in, Then request with the second Request. But yea...

Richard Deeming 6-Jan-23 6:27am

Difficult to answer precisely without knowing exactly what your code is doing. But I've posted an example which might get you a bit further.

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Richard Deeming · Accepted Answer · 2023-01-06T00:25:00

As I mentioned in the comments to solution 1, you don't need to wait for the first request to finish before you start the second request. You just need to wait for the first request to complete before you try to process the second request.

I'd be inclined to store the Promise objects[^] in the queue. Then, when you come to process them, you'll need to await them.

Eg:

JavaScript

class PromiseQueue {
    #queue = [];
    enqueue(promise) {
        this.#queue.push(promise);
    }
    [Symbol.asyncIterator]() {
        return {
            queue: this.#queue,
            async next() {
                if (this.queue.length === 0) {
                    return { done: true };
                }
                
                const promise = this.queue.shift();
                const value = await promise;
                return { done: false, value };
            }
        };
    }
}

// Just for an example - returns a promise which will resolve with the given state after a specified delay:
const waitFor = async (ms, result) => new Promise(resolve => setTimeout(() => resolve(result), ms));

(async () => {
    const taskQueue = new PromiseQueue();
    console.time("TaskQueue");
    
    taskQueue.enqueue(waitFor(2000, "Task 1"));
    taskQueue.enqueue(waitFor(1000, "Task 2"));
    
    for await (let result of taskQueue) {
        console.log(result);
    }
    
    console.timeEnd("TaskQueue");
})();

In this example, the "Task 1" and "Task 2" are output in order, and the total time taken is a touch over 2 seconds. If you'd waited for the first task to finish before starting the second, the total time would have been a touch over 3 seconds.

Edit:
Based on your updated question, I'm guessing you want something like this:

JavaScript

const API  = require('SomeApiWrapperLibrary.js');

class PromiseQueue {
    #queue = [];
    enqueue(promise) {
        this.#queue.push(promise);
    }
    [Symbol.asyncIterator]() {
        return {
            queue: this.#queue,
            async next() {
                if (this.queue.length === 0) {
                    return { done: true };
                }
                
                const promise = this.queue.shift();
                const value = await promise;
                return { done: false, value };
            }
        };
    }
}

(async () => {
    const queue = new PromiseQueue();
    const prefix = ' | ';
    const text = "How's work this week? | It's been pretty good not going to lie. It has been a pretty decent day as well, I like how everything is going this week, |  I hope it get's better."
    
    const Rw = new Api.Client({
        usernameOrEmail: "something",
        password: "somethingelse"
    });
    
    await Rw.start();
    
    const processText = async (textBlock) => {
        const result = await Rw.makeTTS(voice, textBlock);
        return result.Object();
    };
    
    const splitText = text.split(prefix);
    for (const textBlock of splitText) {
        queue.enqueue(processText(textBlock));
    }
    
    for await (let result of queue) {
        console.log(result);
    }
    
    console.log("Done");
})();