JSFiddle - React, Tailwind, and code Playground

HTML

<div>This is the unselectable text</div>

JavaScript

disableSelection(document.body) 

function disableSelection(target){
    if (typeof target.onselectstart!="undefined") //IE route
        target.onselectstart=function(){return false}
    else if (typeof target.style.MozUserSelect!="undefined") //Firefox route
        target.style.MozUserSelect="none"
    else //All other route (ie: Opera)
        target.onmousedown=function(e){if(e && e.target && e.target.tagName){if(/^(input|select)$/i.test(e.target.tagName)){return true;}}return false;}
    target.style.cursor = "default"
}