how to get all elements by class in javascript code example

Example 1: javascript get all elements with class

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

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

Example 2: javascript get all classes

var allHiddenElements = document.getElementsByClassName("hidden");

Example 3: javascript get all elements by class starting with

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