Steps on how to uncompress multiple .gz files using NodeJS and zlib:
1. Import fs and zlib.
var zlib = require(‘zlib’);
var fs = require(‘fs’);
2. Create function to that will decompress files using zlib.createUnzip();.
function decompress(inFilename, outFilename) {
var unzip = zlib.createUnzip();
var input = fs.createReadStream(inFilename);
var output = fs.createWriteStream(outFilename);

input.pipe(unzip).pipe(output);
}

3.  Call function as many times as you need. Please take note that my .gz files are located on assets/models/ folder.
decompress(‘assets/models/CLH_Computer.mtl.gz’, ‘assets/models/CLH_Computer.mtl’);
decompress(‘assets/models/CLH_Computer.obj.gz’, ‘assets/models/CLH_Computer.obj’);
decompress(‘assets/models/CLH_ep2_computer_high_poly.mtl.gz’, ‘assets/models/CLH_ep2_computer_high_poly.mtl’);
decompress(‘assets/models/CLH_ep2_computer_high_poly.obj.gz’, ‘assets/models/CLH_ep2_computer_high_poly.obj’);
decompress(‘assets/models/CLH_ep2_cyc_wall.mtl.gz’, ‘assets/models/CLH_ep2_cyc_wall.mtl’);
decompress(‘assets/models/CLH_ep2_cyc_wall.obj.gz’, ‘assets/models/CLH_ep2_cyc_wall.obj’);
decompress(‘assets/models/CLH_Shuttle.mtl.gz’, ‘assets/models/CLH_Shuttle.mtl’);
decompress(‘assets/models/CLH_Shuttle.obj.gz’, ‘assets/models/CLH_Shuttle.obj’);
4. Put it all together in a .js file and save it as unzip.js on your root folder. If you plan to put everything in one location, just remove assets/models/ from the code.
var zlib = require(‘zlib’);
var fs = require(‘fs’);
function decompress(inFilename, outFilename) {
var unzip = zlib.createUnzip();
var input = fs.createReadStream(inFilename);
var output = fs.createWriteStream(outFilename);

input.pipe(unzip).pipe(output);
}

decompress(‘assets/models/CLH_Computer.mtl.gz’, ‘assets/models/CLH_Computer.mtl’);
decompress(‘assets/models/CLH_Computer.obj.gz’, ‘assets/models/CLH_Computer.obj’);
decompress(‘assets/models/CLH_ep2_computer_high_poly.mtl.gz’, ‘assets/models/CLH_ep2_computer_high_poly.mtl’);
decompress(‘assets/models/CLH_ep2_computer_high_poly.obj.gz’, ‘assets/models/CLH_ep2_computer_high_poly.obj’);
decompress(‘assets/models/CLH_ep2_cyc_wall.mtl.gz’, ‘assets/models/CLH_ep2_cyc_wall.mtl’);
decompress(‘assets/models/CLH_ep2_cyc_wall.obj.gz’, ‘assets/models/CLH_ep2_cyc_wall.obj’);
decompress(‘assets/models/CLH_Shuttle.mtl.gz’, ‘assets/models/CLH_Shuttle.mtl’);
decompress(‘assets/models/CLH_Shuttle.obj.gz’, ‘assets/models/CLH_Shuttle.obj’);
5. Call the unzip.js file by running the following command on your command line.
node unzip.js
There you have it. Hope that helps.