Exercise: Building a Log Filtering Utility

Create a Node.js utility to filter specific lines from large log files and save the results.

We'll cover the following...

Task
Instructions
Sample input
Expected output

Task

Create a Node.js script that reads a large log file and filters out the lines containing the word "ERROR", and writes the remaining lines to a new file.

Instructions

Use fs.createReadStream to read the file logs.txt in chunks.
Create a transform stream to filter out lines containing the word "ERROR". Since a large file may be split across multiple chunks, remember to buffer incomplete lines between chunks rather than splitting each chunk in isolation.
Use fs.createWriteStream to write the filtered logs to filtered-logs.txt.
Pipe the streams together for seamless processing.

Sample input

The following are the contents of sample input file logs.txt: