JSFiddle - React, Tailwind, and code Playground

HTML

<div class="FirstColor">text</div>
<div class="ClassSecond">text</div>

CSS

.FirstColor{
    background: -webkit-gradient(radial, 50% 50%, 0, 50% 50%, 350, from(#ECAA63), to(#E36D0A));
}
.ClassSecond{
    background: -webkit-gradient(radial, 50% 50%, 0, 50% 50%, 350, from(#CEEEEE), to(#98BFF1));
}

JavaScript

var bgGrad = $('.FirstColor').css("background");
var parseRgb = (function (rgbStr) { return rgbStr.match(/rgb\(([0-9]+), ([0-9]+), ([0-9]+)\)/); });
var fromStr = bgGrad.match(/from\((.*)\),/)[1];
var fromRgb = parseRgb(fromStr);

var toStr = bgGrad.match(/to\((.*)\)\)/)[1];
var toRgb = parseRgb(toStr);

alert('From rgb: ' + fromRgb.slice(1,4) + '\nTo rgb: ' + toRgb.slice(1, 4));