npm install protocol-buffers

enum FOO {
  BAR = 1;
}

message Test {
  required float num  = 1;
  required string payload = 2;
}

message AnotherOne {
  repeated FOO list = 1;
}

var protobuf = require('protocol-buffers')

// pass a proto file as a buffer/string or pass a parsed protobuf-schema object
var messages = protobuf(fs.readFileSync('test.proto'))

var buf = messages.Test.encode({
  num: 42,
  payload: 'hello world'
})

console.log(buf) // should print a buffer

var obj = messages.Test.decode(buf)
console.log(obj) // should print an object similar to above

var buf = messages.AnotherOne.encode({
  list: [
    messages.FOO.BAR
  ]
})

var buf = message.SomeMessage.encode({
  list: [
    messages.SomeMessage.NESTED_ENUM.VALUE
  ]
})

Benchmarking JSON (baseline)
  Running object encoding benchmark...
  Encoded 1000000 objects in 2142 ms (466853 enc/s)

  Running object decoding benchmark...
  Decoded 1000000 objects in 970 ms (1030928 dec/s)

  Running object encoding+decoding benchmark...
  Encoded+decoded 1000000 objects in 3131 ms (319387 enc+dec/s)

Benchmarking protocol-buffers
  Running object encoding benchmark...
  Encoded 1000000 objects in 2089 ms (478698 enc/s)

  Running object decoding benchmark...
  Decoded 1000000 objects in 735 ms (1360544 dec/s)

  Running object encoding+decoding benchmark...
  Encoded+decoded 1000000 objects in 2826 ms (353857 enc+dec/s)

var level = require('level')
var db = level('db')

db.put('hello', {payload:'world'}, {valueEncoding:messages.Test}, function(err) {
  db.get('hello', {valueEncoding:messages.Test}, function(err, message) {
    console.log(message)
  })
})