JSFiddle - React, Tailwind, and code Playground

JavaScript

function escapeHtml(unsafe) {
    return unsafe
        .replace(/&/g, "&")
        .replace(/</g, "&lt;")
        .replace(/>/g, "&gt;")
        .replace(/"/g, "&quot;")
        .replace(/'/g, "&#039;");
}

function unescapeHtml(unsafe) {
    return unsafe
        .replace(/&amp;/g, "&")
        .replace(/&lt;/g, "<")
        .replace(/&gt;/g, ">")
        .replace(/&quot;/g, "\"")
        .replace(/&#039;/g, "'");
}

var html = "<&>'\"";
console.log(escapeHtml(html));
console.log(unescapeHtml(html));