JSFiddle - React, Tailwind, and code Playground

JavaScript

// jQuery extension to get an element's outer HTML
// http://stackoverflow.com/a/2419877/1156119
jQuery.fn.outerHTML = function(s) {
    return s
        ? this.before(s).remove()
        : jQuery("<p>").append(this.eq(0).clone()).html();
};

var string = '<div class="preview"><p style="font-size:15px;">....</p><div>'
var elements = $(string);
elements.find('*').removeAttr('style');

var withoutStyles = elements.outerHTML();
alert(withoutStyles);