JavaScript - Interview Puzzles

js-interview-puzzles.js

// What is the output and Why 
const myData = [1,2,3,4];
console.log(myData[4]);
// Answer - undefined


// What is the code below doing and how we can optimize it 

const items = document.querySelctorAll('#container > div');
items.forEach(el => {
  el.addEventListener('click', () => {
      console.log('Event Clicked');
  });
});

// Answer - https://javascript.info/event-delegation

 

// Question - What will happen when we register 2 click events on 1 button


// Why the two this has diffrent values 




var hello = document.getElementById("myId");

hello.addEventListener("click",  () =>   { 
  console.log(this);
});

hello.addEventListener("click", myFunction);

function myFunction(){ 
  console.log("HELLO WORLD 3");
   console.log(this);
}