“Родители, дети” Ответ

Родители, дети

let mainDiv = document.getElementById('main-div');  // First get the div itself

let parent = mainDiv.parentNode;  // the div's parent element
let children = mainDiv.children;  // the div's children
let firstChild = mainDiv.children[0];  // the div's first child
let nextSibling = mainDiv.nextElementSibling;  // the next element at the same nesting level
let prevSibling = mainDiv.previousElementSibling;  // the previous element at the same nesting level