Node.js Streams: Processing Large Files Without Running Out of Memory

The Memory Problem // This will OOM on a 2GB file const data = await fs . readFile ( ' huge-file.csv ' ); // reads entire file into memory const lines = data . toString (). split ( ' \n ' ); // crashes with: JavaScript heap out of memory Streams process data in chunks. You never load the full file—you process pieces as they arrive. Reading Files With Streams import { createReadStream } from ' fs ' ; import { createInterface } from ' readline ' ; async function processCSV ( filePath : string ) { const fileStream = createReadStream ( filePath ); const rl = createInterface ({ input : fileStream , crlfDelay : Infinity }); let lineCount = 0 ; for await ( const line of rl ) { // Process one line at a time — never more than ~1KB in memory const [ name , email , amount ] = line . split ( ' , ' ); await processRecord ({ name , email , amount }); lineCount ++ ; } return lineCount ; } // A 10GB file uses < 50MB of memory await processCSV ( ' ./million-rows.csv ' ); Transform Streams import { Tran