🚀 ES2025 Features: Discover the New Top-Level Await

🤗 Welcome to the first article in my JavaScript ES2025 features series!

In this article, we’ll explore one of the most anticipated additions — Top-Level await. It's a powerful upgrade that makes working with asynchronous code in JavaScript simpler and cleaner, especially inside ES modules.

📌 What Is Top-Level await in JavaScript?

In modern JavaScript, we typically use the async/await combo to handle asynchronous code. Until now, await could only be used inside an async function.

Traditional Way:

const fetchData = async () => {
  const response = await fetch("https://api.example.com/data");
  const data = await response.json();
  console.log(data);
};
fetchData();

With Top-Level await:

Now, with Top-Level await, you can skip the async function wrapper and use await directly — at the top level of your JavaScript module.

const response = await fetch("https://api.example.com/data");
const data = await response.json();
console.log(data);

✅ Cleaner. Simpler. Easier to read.

📂 Where Can You Use Top-Level await ?

Top-Level await only works inside ES modules, which means:

• Your file must use the .mjs extension or

• Your project must include "type": "module" inpackage.json(for Node.js)

• Or you're using a <script type="module">tag in the browser
  

<script type="module">
  const response = await fetch('/config.json');
  const config = await response.json();
  console.log(config);
</script>

🔐 Can You Use Try/Catch?

Absolutely. Error handling with Top-Level await works just like you'd expect:

try {
  const response = await fetch("https://api.example.com/data");
  const data = await response.json();
  console.log(data);
} catch (err) {
  console.error("Error fetching data:", err);
}

🧠 How Top-Level await Works Under the Hood

Although you’re writing plain await at the top level, the JavaScript engine treats it like an async function.

(async () => {
  const response = await fetch("https://api.example.com");
})();

So yes — it's still async! But now, your entire module behaves like an async function, which means:

The code execution pauses at each top-level await

Other modules importing this module will wait until it finishes

🌍 Real-World Use Case

A common scenario: You want to load a config file before initializing your app.

config.js

const res = await fetch('/config.json');
export const config = await res.json();

main.js

import { config } from './config.js';

console.log("Starting app with config:", config);
// app starts here...

This is perfect for loading runtime data like environment variables, feature flags, or user session info.

✅ Advantages of Top-Level await

• 💡 *Cleaner Syntax *– No need to wrap logic inside async functions

• 🚀 Better Flow Control – Pause execution until data is ready

• 📖 Improved Readability – Makes async code look like sync

❌ Disadvantages of Top-Level await

• 🕒 Slower Module Loading – All importing modules must wait

• 📦 *ESM-Only *– Doesn't work in CommonJS (require)

• 🧱 Blocked Execution – Overusing it can hurt performance

🎯 Final Thoughts

Top-Level await is one of the most practical features in ES2025 — it simplifies code, improves structure, and helps you better control async flow. Just make sure to use it where it makes sense, especially in bootstrapping or initialization logic.

Thanks for reading! 🙌

If you found this useful, feel free to share it or drop your thoughts in the comments!

🔗 Connect with me on LinkedIn: linkedin.com/in/parul-verma-pv14

👉 Stay tuned — more exciting ES2025 features coming up soon!