JSFiddle - React, Tailwind, and code Playground

HTML

<p>Test</p>

<p>
sadf
sdf
sadfasfadf
</p>

JavaScript

$(document).on('mouseup', function (e){
    var text = "";
    if (window.getSelection) {
        text = window.getSelection().toString();
    } else if (document.selection && document.selection.type != "Control") {
        text = document.selection.createRange().text;
    }
    alert(text);
});