Answers for "get all elements by class"

javascript get element by class

var elementsArray = document.getElementsByClassName("someclassname");

javascript get all elements with class

const allElementContainGrepperClassName = document.querySelectorAll('.grepper');
// => return array of all elements 

const firstElementContainGrepperClassName = document.querySelector('.grepper');

javascript get all elements by class starting with

document.querySelectorAll("[class^=page]")