npm install messageformat-compile-object --save

var compile = require('messageformat-compile-object');

var obj = {locale: 'es'};

obj.strings = {
  "foo": {
    "bar": "baz!"
  }
};

obj.plural = function (n) {
  return n === 1 ? 'one' : 'other';
};

compile(obj, function (err, fns) {
  fns().foo.bar(); // "baz!"
});

var compile = require('messageformat-compile-object');
var fs = require('fs');
var src = require('./locale');
var dest = ...

compile(src, function (err, fns) {
  var build = 'module.exports = ' + fns.toString();
  fs.writeFileSync(dest, build);
});