Build a Rock-Solid API with Retry & Timeout in 10 Minutes ⏱️

GET /characters?ids=1,2,3

mkdir rickmorty-batch-api
cd rickmorty-batch-api
npm init -y
npm install express oh-no-again

const express = require('express');
const { requestBatcher } = require('oh-no-again');

const app = express();
const PORT = process.env.PORT || 3000;

app.use(express.json());

app.get('/characters', async (req, res) => {
  try {
    const ids = (req.query.ids || '')
      .split(',')
      .map((id) => parseInt(id.trim()))
      .filter(Boolean);

    if (!ids.length) {
      return res
        .status(400)
        .json({ error: 'Please provide character IDs: ?ids=1,2,3' });
    }

    const result = await requestBatcher(
      ids,
      3, // concurrency
      (id) => ({
        url: `https://rickandmortyapi.com/api/character/${id}`,
        method: 'GET',
        headers: { 'Content-Type': 'application/json' },
      }),
      {
        retries: 3,
        delay: 200,
        timeout: 100,
        returnMeta: true,
        hooks: {
          onRetry: (err, attempt) =>
            console.warn(`[RETRY] Attempt ${attempt + 1}: ${err.message}`),
          onFailure: (err) => console.error('[FAILURE]', err.message),
          onSuccess: (res) =>
            console.log('[SUCCESS] Character fetched.', res.name),
        },
      },
    );

    return res.json({ count: result.length, result });
  } catch (err) {
    res.status(500).json({
      error: 'Failed to fetch users',
      message: err.message,
    });
  }
});

app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}`);
});

node server.js

http://localhost:3000/characters?ids=1,2,3,9999

{
  "count": 4,
  "result": [
    {
      "item": 1,
      "result": { "id": 1, "name": "Rick Sanchez", ... },
      "success": true
    },
    {
      "item": 2,
      "result": { "id": 2, "name": "Morty Smith", ... },
      "success": true
    },
    ...
    {
      "item": 9999,
      "error": "Fetch failed with 404 Not Found. Body: {}",
      "success": false
    }
  ]
}

taskFn: (item) => {
  url: string,
  method?: string,
  headers?: Record<string, string>,
  body?: any
}