JSFiddle - React, Tailwind, and code Playground

HTML

<div>Select to insert a node at the start of the selection</div>

JavaScript

document.body.addEventListener('mouseup', insertNode, false);

var node = document.createElement('span');
node.innerHTML = ':)';
function insertNode() {
    var range = document.getSelection().getRangeAt(0);
    range.collapse(true);
    range.insertNode(node);
}