Changing readstream chunksize

This is how you are going to change the change the size of the chunk with highWaterMark : 8 , you can set it to 8,16,24 all are in bytes, be sure if you make chunk size to much high then you are by passing the benefit of using readerstream1. Because benefit of readerstream or stream is that they work efficiently while consuming less memory.

let readerstream1 = fs.createReadStream('shamoon.txt', { highWaterMark: 8 });

According to the ReadStream code, you should be able to increase the highWaterMark by explicitly setting it in the ReadStream options:

var rs = fs.createReadStream('/foo/bar', { highWaterMark: 128 * 1024 });