CODEWITHSUNDEEP
javascriptnode.jsasynchronouslisten
Karim Garali
Karim Garali

Reputation: 85

Nodejs : execute some instructions in an asynchronous way

I want to execute inst1 before inst2 in app.js :

// config/config.js
const readline = require('readline');

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});

module.exports= function() {
    console.log("config.js function");
    rl.question('Run in production environnement (Y|N) ?', (answer) => {
        if(answer === "Y")
            process.env.NODE_ENV = 'prod';
        else
            process.env.NODE_ENV = 'dev';
        rl.close();

    });

}


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

// inst 1
require('./config/config')();
// inst 2
app.listen(port,()=>{
    console.log(`server started on port ${port}`);
});

So as you see here, my function in config.js waits to read a console input. So I want that the app.listen(..) waits until the previous instruction which is my function ends.

How can I proceed ?

Upvotes: 0

Views: 43

Answers (1)

Jonas Wilms
Jonas Wilms

Reputation: 138457

Promisify your first function:

module.exports = new Promise(res => {
  console.log("config.js function");
  rl.question('Run in production environnement (Y|N) ?', res);
}).then(answer => {          
  process.env.NODE_ENV = "Y" ? 'prod' : 'dev';
  rl.close();
});

So you can do this in app.js :

const express = require('express');
const app = express();

(async function(){     
  await require('./config/config');

  app.listen(port, () => {
    console.log(`server started on port ${port}`);
  }); 
})();

Upvotes: 1

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