[Node.js] Reading from the File System in Node.js

There are a handful of ways you can read and write to the File System in Node.js.

We will look at readFileSync, readFile, and a promise based version of readFile.

Each have there use-cases and we will discuss the pros and cons of each one. For instance readFileSync is a blocking operation which if you were developing a web server with Node.js would be a huge problem. With this project being in the CLI for one user, this is a ok option to consider. On the other hand, readFile is a non-blocking operation that uses promises/callbacks to interact with the file system.

// Option 1 - Synchronously, OK for small files

import fs from "fs";

const contents = fs.readFileSync("./data.json");
console.log(contents.toString());

 

 

 // Option 2 - With a callback, async

 import fs from "fs";

 fs.readFile("./data.json", (error, contents) => {
   if (error) {
     console.log(error);
     process.exit(1);
   }
   console.log(JSON.parse(contents.toString()));
 });

 

// Option 3 - with a promise

import fs from "fs/promises";

try {
  const contents = await fs.readFile("./data.json");
  console.log(JSON.parse(contents.toString()));
} catch(err) {
  console.error(err);
  process.exit(1)
}