JSFiddle - React, Tailwind, and code Playground

CSS

.test {
    color: "red"
}

JavaScript

function getStyle(className) {
    var classes = document.styleSheets[0].rules || document.styleSheets[0].cssRules
    for(var x=0;x<classes.length;x++) {
        if(classes[x].selectorText==className) {
                (classes[x].cssText) ? alert(classes[x].cssText) : alert(classes[x].style.cssText);
        }
    }
}
alert( getStyle('.test') + "\n" + getStyle(".clearfix") );