JS - Element properties

element.nextSibling or node.nextSibling: the next sibling of the element; "null" if no next sibling exists.

Coffee (first item)
Tea (second item)

The HTML content of the next sibling of the first list item is :

Note: Whitespace between elements is considered text nodes.
If you add whitespace between the two li elements, the result will be "undefined".

code:

                <div>
                    <ul><li id="item1">Coffee (first item)</li><li id="item2">Tea (second item)</li></ul>
                    <p>The HTML content of the next sibling of the first list item is : <span id="prop">
                    </span></p>
                    <p style="font-size: 0.9vw;"><strong>Note:</strong> Whitespace between elements is
                     considered text nodes.<br>
                    If you add whitespace between the two li elements, the result will be "undefined".</p>
                </div>
                <script>
                    let text = document.getElementById("item1").nextSibling.innerHTML; 
                    document.getElementById("prop").innerHTML = text;
                </script>

JS - element properties - nextSibling

returns the next node at the same node tree level.