How can I store an integer in a nodejs Buffer?

Question

The nodejs Buffer is pretty swell. However, it seems to be geared towards storing strings. The constructors either take a string, an array of bytes, or a size of bytes to allocate.

I am using version 0.4.12 of Node.js, and I want to store an integer in a buffer. Not integer.toString(), but the actual bytes of the integer. Is there an easy way to do this without looping over the integer and doing some bit-twiddling? I could do that, but I feel like this is a problem someone else must have faced at some time.

Answer 1

var buf = new Buffer(4); buf.writeUInt8(0x3, 0); 

http://nodejs.org/docs/v0.6.0/api/buffers.html#buffer.writeUInt8

Answer 2

With more recent versions of Node this is much easier. Here's an example for a 2 byte unsigned integer:

let buf = Buffer.allocUnsafe(2); buf.writeUInt16BE(1234);  // Big endian 

Or for a 4 byte signed integer:

let buf = Buffer.allocUnsafe(4);  // Init buffer without writing all data to zeros buf.writeInt32LE(-123456);  // Little endian this time.. 

The different writeInt functions were added in node v0.5.5.

Have a look at these docs for a better understanding:
Buffer
writeUInt16BE/LE
writeUIntBE/LE
allocUnsafe