How to build properties that can be called or chained

chainable.js

/**
 * Executors
 * ---
 * These perform the final action at each step of the chain.
*/

const keys = Object.create(null);

keys.red = function(str) { return `red(${str})`; },
keys.red.type = "red";
keys.blue = function(str) { return `blue(${str})`; };
keys.blue.type = "blue";
keys.yellow = function(str) { return `yellow(${str})`; };
keys.yellow.type = "yellow";


/**
 * Module
 * ---
 * This exports a module the properties of which can be chained or called.
*/

// Initialise module
function Module(){};
Module.q = [];

// Build chain
function Chain(q, key) {
  // Calling this ends the chain
  function execute(str) {
    q.push(keys[key](str));
    return q.join(",");
  }

  // Otherwise add new value to chain, and pass on
  execute.q = [...q, key];
  return execute;
}

// Define properties. Each property is callable, but also has
// a circular prototype to initial keys
const init = {};
for(const key of Object.keys(keys)) {
  init[key] = {
    get(){
      const self = this; // keep context so the chain remains
      function fn3(){ return Chain(self.q, key); } // add this call's properties in the chain
      fn3.__proto__ = init; // create circular properties to allow chaining
      return fn3(); // build a link in the chain
    }
  };
}

Object.defineProperties(Module.__proto__, init); // Assign first layer of properties to module

module.exports = Module;