Difference Between AJAX And Fetch API
Last Updated :
21 Jun, 2025
Both AJAX and the Fetch API are techniques used in web development to make asynchronous HTTP requests to servers without reloading the entire webpage. This allows web applications to update content dynamically, improving user experience by making web pages faster and more responsive.
- AJAX uses the older XMLHttpRequest object
- Fetch API is a modern, promise-based method for making HTTP requests.
Difference Between AJAX vs Fetch API
Here is a detailed comparison of AJAX And Fetch API based on various features:
Ajax | Fetch API |
|---|
Uses the older XMLHttpRequest object for requests. | Uses the modern fetch() function based on Promises. |
Relies on callback functions to handle responses. | Uses Promises, enabling .then(), .catch(), and async/await. |
Requires manual parsing of response data (e.g., responseText, responseXML). | Provides convenient methods like .json(), .text(), .blob() to parse responses automatically. |
Supports progress events for monitoring upload/download. | Does not natively support progress events (requires additional APIs). |
More verbose and can lead to "callback hell" in complex scenarios. | Cleaner and more readable syntax, especially with async/await. |
Fully supported in all browsers, including very old versions. | Supported in modern browsers; not supported in Internet Explorer without polyfills. |
Provides detailed control over request headers and states via XHR events. | Supports flexible configuration through the Request object and options parameter |
Error handling relies on checking HTTP status codes and onerror events. | Uses Promise rejection for network errors and .catch() for error handling. |
Traditionally used with XML, but commonly with JSON now. | Primarily used with JSON and other modern web formats. |
Often requires more boilerplate code for simple requests. | Allows shorter, more concise code for common request patterns. |
What is AJAX?
AJAX (Asynchronous JavaScript and XML) is a technique that allows web pages to communicate with a server asynchronously without refreshing the whole page. It traditionally uses the XMLHttpRequest (XHR) object to send and receive data, often in XML or JSON format.
Features of AJAX
- Allows asynchronous communication with the server.
- Supports various data formats including XML, JSON, HTML, and plain text.
- Can track progress events like upload and download progress.
- Works well with older browsers, ensuring broad compatibility.
- Allows partial page updates for a smoother user experience.
Uses of AJAX
- Loading new content without page reload.
- Submitting forms asynchronously.
- Real-time data updates such as live search suggestions or chat messages.
- Fetching data for dynamic user interfaces (dashboards, tables, etc.).
What is Fetch API?
The Fetch API is a modern, promise-based JavaScript interface for making HTTP requests. It simplifies the process of fetching resources asynchronously and provides a more powerful and flexible feature set compared to AJAX.
Features of Fetch API
- Based on Promises, making code easier to read and maintain.
- Provides built-in methods to parse JSON, text, blobs, and more.
- Supports request and response streaming.
- More concise syntax, especially when used with async/await.
- Easily configurable with options for headers, credentials, cache, and more.
Uses of Fetch API
- Fetching JSON data from APIs.
- Handling RESTful API requests in modern web apps.
- Performing CRUD operations with better readability.
- Ideal for modern JavaScript applications and frameworks.
Conclusion
AJAX and Fetch API both enable asynchronous server communication, but the Fetch API is a modern, cleaner alternative built on promises that simplify HTTP requests and response handling. While AJAX is still relevant for legacy support and scenarios needing fine-grained control, Fetch API is generally preferred for new development due to its simplicity and better integration with modern JavaScript features like async/await.