Answers for "element.getElementsByClassName"

getelementbyclass

var selector = document.getElementsByClassName('class-name');

get element by class

var elements = document.getElementsByClassName(names); // or:
var elements = rootElement.getElementsByClassName(names);

js get element by class

document.getElementsByClassName('Name');

javascript document object model getElementsByClassName

document.getElementsByClassName('test')

get elment by id within get element byclassname

var targetDiv = document.getElementById("foo").getElementsByClassName("bar")[0];
targetDiv.textContent = "Goodbye world!";