a real use case of fat arrow functions

fatarrows.js

//when function scope sucks, and you have to cache 'this'
let a = function() {
  let that = this;
  this.val = 1;
  setTimeout(function() {
    that.val++;
    console.log(that.val)
  }, 1)
};

//fat arrow to the rescue, 'this' in the context of setTimeout, now uses block scope
let a = function() {
  this.val = 1;
  setTimeout(() => {
    this.val++;
    console.log(this.val)
  }, 1)
};