foo-bar.js

(function (exports) {
  function foo() {
    return 'foo';
  }
  function bar() {
    return 'bar';
  }
  exports.foo = foo;
  exports.bar = bar;
}(typeof module !== 'undefined' ? module.exports : window))

usage.js

var foo = require('foo-bar.js').foo;
var bar = require('foo-bar.js').bar;