How to read binary files byte by byte in Node.js

Question

What is the best way to read part of a binary file in Node.js?

I am looking to either access specific bytes in the \"header\" (less than the first 100 bytes) or read

Answer 1

Here is an example of fs.read()-ing the first 100 bytes from a file descriptor returned by fs.open():

var fs = require('fs');

fs.open('file.txt', 'r', function(status, fd) {
    if (status) {
        console.log(status.message);
        return;
    }
    var buffer = Buffer.alloc(100);
    fs.read(fd, buffer, 0, 100, 0, function(err, num) {
        console.log(buffer.toString('utf8', 0, num));
    });
});