JSFiddle - React, Tailwind, and code Playground

HTML

<input type="button" unselectable onclick="expandSelection();" value="Expand">
<p contenteditable="true" id="test">Hello, this is some test text. Select a word and then press the 'Expand' button.</p>

JavaScript

function expandSelection() {
    if (window.getSelection && window.getSelection().modify) {
        var sel = window.getSelection();
        sel.modify("extend", "forward", "word");
    } else if (document.selection && document.selection.type == "Text") {
        var range = document.selection.createRange();
        range.moveEnd("word", 1);
        range.select();
    }
    document.getElementById("test").focus();
}