Parse Large CSV Files with Streams

Node.jsAdvanced

Essential for backend interviews to prove you understand memory management and non-blocking I/O.

Problem Statement

Write a Node.js script that reads a 5GB CSV file containing user data, extracts users from 'New York', and writes them to a new file, without running out of RAM (heap memory).

Real World Scenario:

Data pipelines constantly process massive files. If you use `fs.readFileSync()`, the entire 5GB file loads into RAM, immediately crashing the Node server.

Input / Output

Input: A file `users.csv` with 50 million rows.

Output: A file `ny_users.csv` containing only the filtered rows.

Constraints

You cannot load the entire file into memory.
You must use the `fs` and `stream` modules.
Max memory usage must stay under 50MB.

Interactive Playground

Console Output

Click "Run Code" to see the output here.