Получение элементов по названию класса
let blueThings = document.getElementsByClassName('blue');
console.log(blueThings); // The HTMLCollection
console.log(blueThings[0]); // The first element with class="blue" in the document
console.log(blueThings.length); // The number of elements with class="blue" found
console.log(blueThings.item(2)); // The element at index 2 in the collection
console.log(blueThings.namedItem('specific')); // The element with both class="blue" and id="specific"
Gorgeous Goldfinch