Arrow function and different between regular function

arrowFunction.js

// Regular Function with "this"

function Car() {
  this.speed = 0;
  this.speedUp = function(speed) {
    this.speed = speed;
  //  let self = this;              ----> without line anonymous function take as shadow from speedUp function.
    setTimeout(function () {
      console.log(self.speed)
    }, 100)
  }
  
}

let car = new Car();
console.log(car.speedUp(20));


// Arrow Function with 'this'
// an arrow function captures the this value of the enclosing context instead of creating its own this context

function Car() {
  this.speed = 0;
  this.speedUp = function(speed) {
    this.speed = speed;
    setTimeout(() => {
      console.log(this.speed)
    })
  }
  
}

let car = new Car();
console.log(car.speedUp(20));