passive_modular.js

// module a.js
let a
function assignValueToA(val) {
  a = val
  calculateValueOfB(a)
}
// module b.js
let b
function calculateValueOfB(a) {
  b = a + 100
}
// main.js
// We assign a value 50 to variable a 
assignValueToA(50)
// b now holds the value 150
console.log(b) // 150
// We change the value of a to 100
assignValueToA(100)
// b now holds the value 200
console.log(b) // 200