JSFiddle - React, Tailwind, and code Playground

JavaScript

var allowedTags = ["div", "span", "h1", "h2", "h3", "h4", "h5", "p", "br", "a", "strong", "em", "li", "ul", "ol", "b", "i", "u", "hr", "font", "pre", "q", "s", "strike", "blockquote", "sub", "sup"];
var wrapper = document.createElement("div");
wrapper.innerHTML = "<h1>Your HTML here</h1><p>Test</p><span><audio /></span>";
function walk(element) {
    var el = element;
    var len = el.childNodes.length, i;
    for(i = 0; i<len; i++) {
        if(!walk(el.childNodes[i])) return false;
    }
    return !(el.tagName && allowedTags.indexOf(el.tagName.toLowerCase()) === -1);
}
var result = !walk(wrapper);
console.log("Contains invalid tags: " + result);