Read gzip stream line by line

It might be easier to use readline for this:

const fs       = require('fs');
const zlib     = require('zlib');
const readline = require('readline');

let lineReader = readline.createInterface({
  input: fs.createReadStream('test.gz').pipe(zlib.createGunzip())
});

let n = 0;
lineReader.on('line', (line) => {
  n += 1
  console.log("line: " + n);
  console.log(line);
});

If anyone is still looking into how to do this years later, and wants a solution that works with async/await, here's what I'm doing (TypeScript, but you can just ditch the type annotations).

import fs from "fs";
import zlib from "zlib";
import readline from "readline";

const line$ = (path: string) => readline.createInterface({
    input: fs.createReadStream(path).pipe(zlib.createGunzip()),
    crlfDelay: Infinity
});

const yourFunction = async () => {
    for await (const line of line$("/path/to/file.txt.gz")) {
        // do stuff with line
    }
}