how to get an element by class name in javascript code example

Example 1: javascript get element by class

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

Example 2: get element by class

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

Example 3: get element by class

var x = document.getElementsByClassName("example");
var i;
for (i = 0; i < x.length; i++) {
  x[i].style.backgroundColor = "red";
}