redis connection + singleton + node.js

Question

I am using redis to store sessions in my project.

In app.js

var client  = redis.createClient();

client.on('error', function (err) {
  console.log('could not establish a connection with redis. ' + err);
});
client.on('connect', function (err) {
  console.log('connected to redis successfully');
});

In my routes.js files i have to get all information from redis, so i am using the following:

var client = redis.createClient();

client.on('error', function(err){
  console.log('Something went wrong ', err)
});

But everytime its connecting to redis. How can i connect redis once in my app.js and use it everywhere. please suggest ideas. Thanks in advance.

EDIT

app.js

module.exports.client = client;

routes.js

var client = require("../app.js").client;
client.hgetall();

But i am receiving error

TypeError: Cannot read property 'hgetall' of undefined

Answer 1

In app.js

var client  = redis.createClient();

client.on('error', function (err) {
  console.log('could not establish a connection with redis. ' + err);
});
client.on('connect', function (err) {
  console.log('connected to redis successfully');
});

module.exports = { client }

In routes.js

var { client } = require('./app');

client.on('error', function(err){
  console.log('Something went wrong ', err)
});

(Assuming app.js and routes.js are in same level of directory)

EDIT: fixed few typo

Answer 2

app.js

    const redis = require('redis'),
redisClient = redis.createClient(6379, '127.0.0.1');
const http = require('http');

const REDIS_USER_DATA_INDEX = 2;

redisClient.select(REDIS_USER_DATA_INDEX);

module.exports.client = redisClient;

routes.js

    const app = require('./app');

app.client.on('connect', function () {
    console.log('redis connected');
    console.log(`connected ${app.client.connected}`);
}).on('error', function (error) {
    console.log(error);
});

I hope this will resolve your issue. Thanks