ES6+ Features

What is the output?

const [a, , b] = [1, 2, 3]
console.log(a, b)

What does this output?

function sum(first, ...rest) {
  return first + rest.reduce((a, b) => a + b, 0)
}
console.log(sum(1, 2, 3, 4))

Spot the issue:

const name = "Rahul"
const msg = "Hello, ${name}!"
console.log(msg)