Using await in node.js

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I have a function that reads files in a directory and pushes their name into an array. But every time I try to print the array, it's empty because the code does not wait for the function to finish, even though I used await that suppose to make the code wait for the function.

here is the code:

let filesToMove = [];

async function readFiles() {
  const testFolder = "./files_to_move/";

  fs.readdir(testFolder, (err, files) => {
    files.forEach((file) => {
        filesToMove.push(file);
      console.log("done");
    });
  });
}

async function printFiles() {
  files = await readFiles();

  console.log(filesToMove.length);
  filesToMove.forEach((item) => {
      console.log(item);
  });
}

Thank you in advance

What I have tried:

I don't really know what to try. I new at this. I would appreciate any material that can help me understand.

Posted 11-Jun-22 22:03pm

canvas_newbi

Updated 12-Jun-22 22:24pm

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Richard Deeming · Answer 1 · 2022-06-12T22:24:00

Your readFiles function does not return a Promise. The printFiles function has nothing to await.

If you're using Node.js v10 or later, you can use fsPromises.readdir[^] instead:

JavaScript

import { readdir } from 'node:fs/promises';

async function readFiles() {
  const testFolder = "./files_to_move/";
  return await readdir(testFolder);
}

async function printFiles() {
  const filesToMove = await readFiles();
  console.log(filesToMove.length);
  filesToMove.forEach(item => console.log(item));
}

Otherwise, you'd need to convert the call to a promise and return that:

JavaScript

function readFiles() { /* NB: Not "async" */
  const testFolder = "./files_to_move/";
  return new Promise((resolve, reject) => {
    fs.readdir(testFolder, (err, files) => {
      if (err) {
        reject(err);
      } else {
        resolve(files);
      }
    });
  });
}

async function printFiles() {
  const filesToMove = await readFiles();
  console.log(filesToMove.length);
  filesToMove.forEach(item => console.log(item));
}

Using await in node.js

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Using await in node.js

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