Here is an example:

var container = document.querySelector('#example');

//Create shadow root !

var root = container.createShadowRoot();

root.innerHTML = '<div>Root<div class=test>Element in shadow</div></div>';



//Access the element inside the shadow !

//container.shadowRoot represents the youngest shadow root that is hosted on the element !

console.log(container.shadowRoot.querySelector(.test).innerHTML);

Demo:

var container = document.querySelector('#example');

//Create shadow root !

var root = container.createShadowRoot();

root.innerHTML = '<div>Root<div class=test>Element in shadow</div></div>';



//Access the element inside the shadow !

console.log(container.shadowRoot.querySelector(.test).innerHTML);

<div id=example>Element</div>

I hope this will help you.