Relative fs.readFileSync paths with Node.js

In this post you’ll learn how to use fs.readFileSync to give you a relative path to your asset.

By default, that’s not the case and Node.js looks at the root of the project directory - so we’re here to change that.

🕵️‍♂️ File System String path docs: String form paths are interpreted as UTF-8 character sequences identifying the absolute or relative filename. Relative paths will be resolved relative to the current working directory as determined by calling process.cwd().

I was recently coding a Node.js API and needed to access an image to add into a PDF. This meant using fs (filesystem) from Node.js like so:

import fs from 'fs';

const logo = fs.readFileSync('./assets/img/logo.svg');

This worked just fine, when the assets/ folder was in the root of my project. But I moved it into a sub-folder, which then meant everything blew up.

Turns out, you need to use path.resolve alongside __dirname to make it relative:

import fs from 'fs';
import path from 'path';

const logo = fs.readFileSync(path.resolve(__dirname, './assets/img/logo.svg'));

I like to architect my Node.js apps in TypeScript, so below I’ll add the CommonJS syntax.

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So, if you’re using CommonJS imports with require then you’ll have something like this instead:

const fs = require('fs');
const path = require('path');

const logo = fs.readFileSync(path.resolve(__dirname, './assets/img/logo.svg'));

🙌 If you want to learn even more, I’ve built a bunch of TypeScript Courses which might just help you level up your TypeScript skills even further. You should also subscribe to our Newsletter!

Happy coding, and thanks for reading!