find a child element by class code example

Example 1: javascript element by class

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

Example 2: get all the child of the same class javascript

var doc = document.getElementById("test");
var notes = null;
for (var i = 0; i < doc.childNodes.length; i++) {
    if (doc.childNodes[i].className == "4") {
      notes = doc.childNodes[i];
      break;
    }        
}