JSFiddle - React, Tailwind, and code Playground

by carsont

HTML

<div id="bg"></div>

CSS

#bg {
    width: 50px;
    height: 50px;
}

JavaScript

$(function () {
    var $bg = $('#bg');
    
    $bg.css("background-image", 'url("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAGUlEQVQIW2NkwAIYCQn+Z2BgACsiqBJuEgA0oAEG+FuXFQAAAABJRU5ErkJggg==")');

    window.onbeforeunload = function (e) {
        $bg.css("background-image", 'url("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAoAAAAKCAYAAACNMs+9AAAATklEQVQYV2O0O3X+PwMDA8MhM0NGEI0LMBKtEJsJD27YgW1R0DgEtwWrdUQrxGYLY8V5iDUdhghrKFOITfenmXFgW/jSF+H3DNEKsdkCAO99IAvSBrFVAAAAAElFTkSuQmCC")');
        
        setTimeout(function() {window.width = window.width;}, 0);
        
        return "Don't leave";
    };
});