Encapsulating methods behind Getters

Question

I'm developing a website using the node.js/express stack and I'm trying to develop in the functional style which is pretty new to me. The express method res.send requires the function to be called as a method because it refers to this in the body, but calling methods doesn't work naturally in the functional style.

You can put the method behind a getter function that turns it into a function, but I don't know if there are any downsides to this other than code complexity?

Example:

(function() {
"use strict";

function Foo() {
  function bar() {
    console.log(this.x);
  }
  return {
    bar,
    get baz() {
      var s = this;
      return () => s.bar();
    }
  }
}

var a = new Foo();
a.x = 5;
a.bar();
a.baz();

var b = a.bar;
var c = a.baz;
//b(); // throws an error because `this` is not defined
c();

function wrapper(f) {
  f();
}

//wrapper(a.bar); // throws an error
wrapper(a.baz);

})();

Answer 1

Ultimately it depends on your exact use-case, but adding wrapper functions is pretty typical in javascript and Node and is unlikely to add any downsides. You can fix the error you're seeing when calling wrapper(a.bar); // throws an error with the use of bind, as below:

wrapper(a.bar.bind(a));

Calling bind will ensure that this is set to appropriately when the function is called later.

Here is a demo: https://jsfiddle.net/zuL9g98m/