Node.js csvtojson - return result outside of function

Question

I am relatively new to this and haven't quite got my head round how this all works...

Basically I am using the csvtojson function to convert a csv file into json. This works fine and outputs the json array to the console.log.

After performing this action I want to take the json array returned and do some extra things to it e.g outputting to a file.

My question is how do use the array outside of the function where it is created, Alternatively should I be writing the code within the function?

This is my code:

const csvFilePath='./test.csv'
const csv=require('csvtojson')

csv()
.fromFile(csvFilePath)
.then((jsonObj)=>{
    console.log(jsonObj);
//should I write code here 
});


console.log(jsonObj);
//This returns jsonObj is not defined
//how do I/Can I read jsonObj here

Can someone help me understand what I need to do here please?

Answer 1

Because csv() function is asynchronous and returns a Promise object. You can read the value inside of the .then() function.

---

How the interpretor sees the code :

// Create a variable and store a data inside
const csvFilePath='./test.csv'

// Create a variable and store a data inside
const csv=require('csvtojson')

// Call the function csv().fromFile(csvFilePath), because it's asynchronous
// deal with the result later
csv()
.fromFile(csvFilePath)
.then((jsonObj)=>{
    console.log(jsonObj);
});

// Display the content of the variable jsonObj
// jsonObj is not declared, display 'undefined'
console.log(jsonObj);

// Leave the current function

after some time

// Execute the .then function
.then((jsonObj)=>{
   // Display the content of the variable jsonObj
   console.log(jsonObj);
});

---

Here is a demonstrating snippet

const asynchronousFunction = () => new Promise((resolve) =>
  setTimeout(() => resolve('asynchronous'), 1000));

const ret = 'not initialized';

asynchronousFunction()
  .then((ret) => {
    console.log(ret);
  });

console.log(ret);