JSFiddle - React, Tailwind, and code Playground

HTML

Select some content on this page and use the buttons below.<br><br>
<button onclick="storeSelection();">Store the selection</button>
<button onclick="clearStoredSelections();">Clear stored selections</button>
<button onclick="showStoredSelections();">Show stored selections</button>

CSS

.highlight
{
    background: Highlight;
}

JavaScript

var storedSelections = [];
var simulatedSelections = [];

window.onmousedown = clearSimulatedSelections;

function storeSelection()
{
    if(window.getSelection)
    {
        var currSelection = window.getSelection();
        for(var i = 0; i < currSelection.rangeCount; i++)
        {
            storeRecursive(currSelection.getRangeAt(i));
        }
        currSelection.removeAllRanges();
    }
    else
    {
        alert("Your browser does not support this example!");
    }
}

function storeRecursive(selection, node, started)
{
    node = node || document.body;
    started = started || false;
    var nodes = node.childNodes;
    for(var i = 0; i < nodes.length; i++)
    {
        if(nodes[i].nodeType == 3)
        {
            var first = nodes[i] == selection.startContainer;
            var last = nodes[i] == selection.endContainer;
            if(first)
            {
                started = true;
            }
            if(started)
            {
                var sel = selection.cloneRange();
                if(!first)
                {
                    sel.setStartBefore(nodes[i]);
                }
                if(!last)
                {
                    sel.setEndAfter(nodes[i]);
                }
                storedSelections.push(sel);
                if(last)
                {
                    return false;
                }
            }
        }
        else
        {
            started = storeRecursive(selection, nodes[i], started);
        }
    }
    return started;
}

function clearStoredSelections()
{
    storedSelections = [];
}

function showStoredSelections()
{
    if(window.getSelection)
    {
        var currSelection = window.getSelection();
        currSelection.removeAllRanges();
        for(var i = 0; i < storedSelections.length; i++)
        {
            var node = document.createElement("span");
            node.className = "highlight";
            storedSelections[i].surroundContents(node);
           ...