Should I require in each module? - node.js

Question

I don't know how to structure my code or rather I don't know what happens when an app is built with the below structure. I need to use redis, so is it ok to call it in each module or is this a bad practice?
I have 10 functions that I want to have in separate modules to keep my code readable. I am using express js.
So I have an index.js which looks like this:
const express = require("express");
const app = express();
const port = 3001;
// the separate modules I want to make
let myFirst = require("./first_function");
let mySecond = require("./second_function");
//etc...
app.use("/my_route1",myFirst);
app.use("/my_route2",mySecond);
app.listen(port, () => console.log(`Listnening on port ${port}`));
The first_function.js file looks like this:
const express = require("express");
const router = express.Router();
const redis = require("redis");
const { promisify } = require("util");
const REDISHOST = process.env.REDISHOST;
const REDISPORT = process.env.REDISPORT;
const redisClient = redis.createClient(REDISPORT, REDISHOST);
const getAsync = promisify(redisClient.get).bind(redisClient);
redisClient.on("error", function(err) {
return;
// but since this is an http function should I be calling res.end()?
});
router.all("/", (req,res) =>{
// code for my function
});
module.exports = router;
I will be using redis in quite a few of the modules, so would it just be better to make the index.js file thousands of lines of code or whatever it may come out to be? I don't quite understand what happens when a module is required, if I use 10 modules which all require redis and then require those modules from index.js will I end up with 10 redis clients?

Answer 1

const redis = require('redis');
class Connection {
constructor() {
this.redisClient = redis.createClient({host : "<hostname>", port : "<port>"});
let methods = {};
methods.redisF = false;
if(this.redisconf.cache) {
this.redisClient.on('ready',function() {
methods.redisF = true;
console.log(" Redis cache is up and running ... ");
});
}
this.redisClient.on('error',function() {
methods.redisF = false;
});
}
static makeRedisConnection() {
try {
return this.redisClient;
} catch(error) {
throw "error"
}
}
}
module.exports = Connection;
Whenever you want to query from redis, take the connection in any of the async function from any other module in the below manner, it will help you write less and more structured code.
const redis_conn = Connection.makeRedisConnection();