Read json file content with require vs fs.readFile

Question

Suppose that for every response from an API, i need to map the value from the response to an existing json file in my web application and display the value from the json. Wh

Answer 1

Since no one ever cared to write a benchmark, and I had a feeling that require works faster, I made one myself.

I compared fs.readFile (promisified version) vs require (without cache) vs fs.readFileSync.

You can see benchmark here and results here.

For 1000 iterations, it looks like this:

require: 835.308ms
readFileSync: 666.151ms
readFileAsync: 1178.361ms

So what should you use? The answer is not so simple.

1. Use require when you need to cache object forever. And better use Object.freeze to avoid mutating it in application.
2. Use readFileSync in unit tests or on blocking application startup - it is fastest.
3. Use readFile or promisified version when application is running and you don't wanna block event loop.