Useful javascript tips

jsTips.md

IIFE

const increaseCounter = (function() {
  let counter = 0;
 
  return function() {
    counter = counter + 1;
    console.log(counter);
  };
})();

The IIFE run only once and initialize the counter variable with 0 then returns a function that can access the counter variable. So, when you call increaseCounter(), it will update the counter as expected.