adder.js

'use strict';
function createAdderJob(val) {
  return function adder(g) {
    g.entry = g.entry.map(src => src + val);
    return g;
  }
}

module.exports = createAdderJob;

init.js

'use strict';
const createAdder = require('./adder');
const createMuller = require('./muller');

function init(g) {
  const adder = createAdder(10);
  const muller = createMuller(2);

  return Promise.resolve(g)
    .then(adder)
    .then(muller);
}


// start
init({
  entry: [1, 2, 3, 4, 5]
}).then(console.log);

muller.js

'use strict';
function createMullerJob(val) {
  return function muller(g) {
    g.entry = g.entry.map(src => src * val);
    return g;
  }
}

module.exports = createMullerJob;