JS Closure Example (1)

js-closure-example-1.js

const counter = () => {
  let privateCounter = 0;
  
  const changeBy = (val) => {
    privateCounter += val;
  }
  
  return ({
    increment: () => {
      changeBy(1);
    },
    decrement: () => {
      changeBy(-1);
    },
    value: () => {
      return privateCounter;
    }
  });   
};

const counterFunc = counter();

console.log(counterFunc.value()); // 0

counterFunc.increment();
counterFunc.increment();
console.log(counterFunc.value()); // 2

counterFunc.decrement();
console.log(counterFunc.value()); // 1