Answers for "document get element by class calculate all value"

javascript get all elements with class

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

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

document getelementsbyclassname not getting all elements

//use this instead
document.querySelectorAll(".myclassname");