Firebase SDK is plug and play

Blog with comments...

*consider rules with DB codepen is purely an example

initialize

const firebaseConfig = {
apiKey: "YOUR_API_KEY",
authDomain: "YOUR_AUTH_DOMAIN",
databaseURL: "YOUR DATABASE URL".
projectid: "YOUR_PROJECT_ID",
storageBucket: "YOUR_ STORAGE _BUCKET",
messaging Senderld: "YOUR_MESSAGING_SENDER_ID",
appld: "YOUR_APP_ID"
measurementld: "YOUR_ MEASUREMENT_ID"
};

if (!firebase.apps.length) {
  firebase.initializeApp(firebaseConfig);
}

read, write, and display comments

var database = firebase.database();

var commentsContainer = document.getElementById("comments-container");

function displayComments() {
  database.ref("comments").on("value", function (snapshot) {
    commentsContainer.innerHTML = "";
    snapshot.forEach(function (childSnapshot) {
      var comment = childSnapshot.val().text;
      var timestamp = new Date(childSnapshot.val().timestamp);

      var commentElement = document.createElement("div");
      commentElement.classList.add("comment");

      var commentTextElement = document.createElement("div");
      commentTextElement.classList.add("comment-text");
      commentTextElement.textContent = comment;
      commentElement.appendChild(commentTextElement);

      var timestampElement = document.createElement("div");
      timestampElement.classList.add("comment-timestamp");
      timestampElement.textContent = timestamp.toLocaleString();
      commentElement.appendChild(timestampElement);

      commentsContainer.appendChild(commentElement);
    });
  });
}

displayComments();

document
  .getElementById("comment-form")
  .addEventListener("submit", function (event) {
    event.preventDefault();
    var commentInput = document.getElementById("comment-input").value;
    if (commentInput.trim() !== "") {
      var newCommentRef = database.ref("comments").push();
      newCommentRef.set({
        text: commentInput,
        timestamp: firebase.database.ServerValue.TIMESTAMP
      });
      document.getElementById("comment-input").value = "";
    }
  });

css to fit your style

body {
  font-family: Arial, sans-serif;
  background-color: #748b97;
  margin: 0;
  padding: 0;
}

.container {
  max-width: 560px;
  margin: 14px auto;
  padding: 14px;
  background-color: #fff;
  border-radius: 8px;
  box-shadow: 0 0 7px rgba(0, 0, 0, 0.1);
}

h1 {
  text-align: center;
}

img {
  max-width: 100%;
  height: auto;
  margin-bottom: 14px;
  border-radius: 8px;
}

#comments-container {
  margin-bottom: 14px;
}

.comment {
  background-color: #f9f9f9;
  padding: 10px;
  border-radius: 8px;
  margin-bottom: 10px;
  border: 1px solid #ddd;
}

.comment-text {
  margin-bottom: 5px;
}

.comment-timestamp {
  color: #888;
  font-size: 0.9em;
}

#comment-form {
  display: flex;
}

#comment-input {
  flex: 1;
  margin-right: 10px;
  padding: 8px;
  border: 1px solid #ddd;
  border-radius: 4px;
}

button {
  padding: 8px 16px;
  cursor: pointer;
  background-color: #007bff;
  color: #fff;
  border: none;
  border-radius: 4px;
}

button:hover {
  background-color: #0056b3;
}

Blog with comments...