Example of change state in js-modules

composition.js

var state = require('./state');
var f1 = require('./f1'); 
var f2 = require('./f2');
try{
   f1();//Change state, really bad
   var newState =  f2();// pure function
   //await f3
   //yield* f4
}catch(e){
  
}

f1.js

var state = require('./state');
module.exports = ()=>{
  state.x = state.x + 1;
  console.log(state.x); //side effect
}

f2.js

var state = require('./state');
module.exports = ()=>{
  state = Object.assign({}, state);
  state.y = state.y + 2;
  return state;
}

state.js

var state = {
  x: 1,
  y: 1
}
module.exports = state;