how to access child element in javascript code example

Example 1: get child of child javascript

var li = document.querySelector("li");
var number = 13;
li.children[0].children[0].innerHTML = number;

Example 2: select child javascript

Syntax
element.children

Example
Change the background color of the second child element of a <div> element:

var c = document.getElementById("myDIV").children;
c[1].style.backgroundColor = "yellow";