Should I split json-data by categories to return express server?

I’m working on a simple App using React and express server(to learn React Redux)
So I’ve created a simple Express server app in order to return JSON with products data. And I’m not sure - should I return the whole JSON with products or filter it by category - like I’ve done it and return small part depending on users category choice?
In my small app it doesn’t matter of course. But I’m interested to know some good practices)
Here’s a code of express:

  /* eslint no-console: 0 */
const express = require('express');
const cors = require('cors');
const fs = require('fs');

const buffer = fs.readFileSync('./data.json');
const productsObj = JSON.parse(buffer);
const app = express();

app.get('/:category', (req, res) => {
  const selectedProducts = productsObj.products.filter(item => item.category === req.params.category);
  if (selectedProducts) {
setTimeout(() => res.json(selectedProducts), Math.floor(Math.random() * 1000));
  } else {
console.log(404, req.params.category);
res.status(404).json({ error: 'category not found' });

console.log(`Starting server on port 3000`);
console.log(`Generating api with products`);

Definitely filter by category. It doesn’t make sense to retrieve more data than you need.

But I’m worried about drawbacks of this approach. In this case every time a user choose another category - api request is being made.

Results from http requests get cached so that is not really a problem. Sending a list with likely thousands of products can be a problem on the other hand.