StevenWuTG

/first you need to find a parent element node
const parent2 = document.querySelector("#parent-2")

const child1Ofparent2 = parent2.childNodes[0]
//this will return the child-3 node which is at the first index of parent2

const child2Ofparent2 = parent2.childNodes[1]
//this will return the child-4 node which is at the second index of parent2

StevenWuTG

const ballBoundaries = () => {
    // Bounce off Left Wall
    if (ballX < 0 && speedX < 0) {
      speedX = -speedX
    }
    // Bounce off Right Wall
    if (ballX > width && speedX > 0) {
      speedX = -speedX
    }
    // Bounce off player paddle (bottom)