test.js

const {Layer, Network} = require('synaptic');
const inputLayer = new Layer(2);
const hiddenLayer = new Layer(3);
const outputLayer = new Layer(1);

inputLayer.project(hiddenLayer);
hiddenLayer.project(outputLayer);

const myNetwork = new Network({
  input: inputLayer,
  hidden: [hiddenLayer],
  output: outputLayer,
});

const learningRate = 0.3;

for (let i = 0; i < 1000000; i++) {

  // 1+1 => 2
  myNetwork.activate([.1, .1]);
  myNetwork.propagate(learningRate, [.2]);

  // 2+2 => 4
  myNetwork.activate([.2, .2]);
  myNetwork.propagate(learningRate, [.4]);

  // 1+2 => 3
  myNetwork.activate([.1, .2]);
  myNetwork.propagate(learningRate, [.3]);

  // 1+7 => 8
  myNetwork.activate([.1, .7]);
  myNetwork.propagate(learningRate, [.8]);
}

console.log('');

console.log(Math.round(myNetwork.activate([.1,.0])*10));
console.log(Math.round(myNetwork.activate([.6,.1])*10));
console.log(Math.round(myNetwork.activate([.2,.6])*10));
console.log(Math.round(myNetwork.activate([.1,.1])*10));