Comparing Fetch API and AJAX: What’s the Difference

Last Updated on September 29, 2023

Introduction

Fetch API and AJAX are two technologies commonly used for making asynchronous requests in web development.

Fetch API is a modern API introduced in JavaScript to handle HTTP requests and responses.

It is built into the window object and provides a more powerful and flexible way to make network requests.

AJAX, short for Asynchronous JavaScript and XML, is a technique that allows web pages to update content dynamically without reloading the entire page.

It was widely used before the introduction of Fetch API.

Understanding the differences between Fetch API and AJAX is essential for web developers to make informed decisions and choose the best approach for their applications.

While both technologies serve a similar purpose, there are notable differences in terms of syntax, flexibility, browser support, and handling of requests and responses.

Fetch API offers a cleaner and more concise syntax, utilizing promises for handling asynchronous operations.

It also supports newer features like cross-origin resource sharing (CORS) and the ability to stream response data.

AJAX, on the other hand, has been around for a longer time and enjoys better backward compatibility with older browsers.

It is still widely used in legacy systems and offers a larger community and libraries built around it.

By understanding the differences, developers can choose the appropriate technology for their specific needs and ensure compatibility across different browsers and systems.

In fact, both Fetch API and AJAX are important technologies for making asynchronous requests in web development.

Understanding their differences will help developers make informed decisions and build efficient and reliable applications.

Explaining Fetch API

Fetch API is a modern technology for making asynchronous network requests in web browsers.

It simplifies the process of communicating with a server and retrieving data.

Here is an explanation of Fetch API, its purpose, usage, and how it differs from the traditional AJAX method.

Definition and Purpose of Fetch API

1. Fetch API is a web standard that provides an interface for fetching resources, such as JSON, XML, or HTML, over the network.
   
   
2. Its purpose is to improve upon the limitations of the older XMLHttpRequest (XHR) object used for AJAX requests.

Basic Syntax and Usage Examples

1. The Fetch API is straightforward to use. To make a request, you simply call the fetch() function and provide the URL of the resource you want to fetch.
   
   
2. For example, to fetch a JSON file, you would write: fetch(‘https://example.com/data.json’).

Built-in Support for Promises and Simplifying Asynchronous Requests

1. One significant advantage of Fetch API is its built-in support for promises, which simplifies handling asynchronous requests.
   
   
2. Instead of using callbacks, you can use promises to handle responses and perform actions once the data is retrieved.

Support for Response Types and Handling Various Data Formats

1. Fetch API supports multiple response types, such as JSON, ArrayBuffer, Blob, and more.
   
   
2. You can specify the desired response type using the response type property of the options object passed to the fetch() function.

Cross-Origin Resource Sharing (CORS) and Fetch API

1. Fetch API respects the Cross-Origin Resource Sharing protocol, which allows server owners to control who can access their resources.
   
   
2. It automatically sends the necessary CORS headers and handles the response based on the server’s configuration.

In short, Fetch API offers a more modern approach to making asynchronous requests in web browsers compared to traditional AJAX methods.

Its simplicity, support for promises, various response types, and adherence to CORS make it a powerful tool for fetching data from servers.

Read: How to Use Promises and Async/Await with AJAX

Explaining AJAX

Definition and purpose of AJAX (Asynchronous JavaScript and XML)

AJAX, or Asynchronous JavaScript and XML, is a web development technique that allows for asynchronous communication between a client and server.

It enables web applications to retrieve data from the server without refreshing the entire page, resulting in a more dynamic user experience.

XMLHttpRequest object and its role in making asynchronous requests

The XMLHttpRequest object is a key component of AJAX.

It provides the ability to send HTTP requests to the server and handle responses without blocking the user interface.

By using this object, developers can perform various types of requests, such as GET or POST, and retrieve data in different formats, including XML, JSON, or plain text.

Handling response data and updating the DOM dynamically

Once a request is made using AJAX, the response data can be processed and dynamically updated in the Document Object Model (DOM) of the web page.

This enables real-time updates and allows for the seamless display of new content without requiring a full page reload.

Differences between synchronous and asynchronous requests

1. In synchronous requests, the browser waits for the server’s response before continuing with other operations.
   
   
2. This can lead to a poor user experience as the page may freeze until the response is received.
   
   
3. Asynchronous requests don’t block the UI, enabling concurrent operations and improving application responsiveness.

Cross-origin resource sharing (CORS) and AJAX

Cross-Origin Resource Sharing (CORS) is a security mechanism that restricts AJAX requests made from a web page to a different origin (domain, protocol, or port).

It requires the server to include specific HTTP headers to allow or deny cross-origin requests.

Without proper CORS configuration, AJAX requests may be blocked by the browser for security reasons.

Read: AJAX File Upload: A Comprehensive Tutorial

Key Differences between Fetch API and AJAX

When it comes to making asynchronous requests to a server, developers have traditionally relied on AJAX.

However, with the introduction of the Fetch API in modern browsers, there is now a newer and more powerful alternative.

Fetch API is more modern and provides a cleaner, promise-based syntax

The first major difference between Fetch API and AJAX is the syntax.

Fetch API provides a cleaner and more straightforward way to make HTTP requests, thanks to its promise-based approach.

This means that instead of using callbacks like in AJAX, you can use promises and take advantage of their benefits, such as chaining and error handling.

AJAX relies on the XMLHttpRequest object, which has been around for longer

1. Another key difference is the underlying object used to perform the requests.
   
   
2. AJAX uses the XMLHttpRequest object, which has been around for a long time and is supported by all major browsers.
   
   
3. On the other hand, Fetch API uses the fetch function that returns a promise, making it more modern and easier to use.

Fetch API has better support for handling various data formats

1. Fetch API also has better built-in support for handling different data formats.
   
   
2. It supports JSON natively, which is the most common data format used in web development.
   
   
3. Additionally, it provides methods to handle other formats like XML and FormData without the need for additional plugins or libraries.

AJAX requires additional configuration while Fetch API has built-in support for CORS

1. One major advantage of Fetch API over AJAX is its built-in support for Cross-Origin Resource Sharing (CORS).
   
   
2. CORS is a security mechanism that enables requests to be made from one origin to another.
   
   
3. Fetch API automatically handles CORS headers, allowing for seamless cross-origin communication.
   
   
4. In contrast, AJAX requires additional configuration to handle CORS requests properly.

Fetch API supports streaming responses, while AJAX does not

1. Another feature that sets Fetch API apart is its support for streaming responses.
   
   
2. With Fetch API, you can stream and process the response data incrementally as it arrives, which is useful for handling large or dynamically generated data.
   
   
3. AJAX, on the other hand, does not support streaming responses, requiring the entire response to be loaded before it can be processed.

In essence, while both Fetch API and AJAX serve the purpose of making asynchronous requests, Fetch API offers several key advantages.

It provides a cleaner syntax, better support for data formats, built-in CORS support, and the ability to stream responses.

As a result, Fetch API has become the preferred choice for many developers working on modern web applications.

Read: Managing Databases with Python’s SQLite Module

Use Cases for Fetch API and AJAX

When it comes to making asynchronous HTTP requests, developers have traditionally relied on AJAX.

However, with the introduction of the Fetch API, there is now an alternative method that offers some distinct advantages.

In this section, we will explore the use cases for Fetch API and AJAX, helping you understand when to use each one.

Fetch API is recommended for new projects and modern browsers

1. The Fetch API is a modern JavaScript interface that provides a more powerful and flexible way to fetch resources.
   
   
2. It supports promises, allowing you to use async/await syntax for handling asynchronous requests.
   
   
3. Fetch API provides a more consistent and simplified API compared to the complex XMLHttpRequest object used by AJAX.
   
   
4. It offers built-in support for handling various data formats such as JSON, FormData, and more.
   
   
5. Fetch API is well-supported by modern browsers, making it an ideal choice for new projects.

AJAX might be more suitable for legacy systems or environments with limited browser compatibility

1. AJAX has been around for a long time and is widely supported by older browsers, making it a suitable choice for legacy systems.
   
   
2. If you need to support older browsers or work in an environment with limited browser compatibility, AJAX can be a reliable option.
   
   
3. It provides more control over the request and response process, allowing fine-grained customization.
   
   
4. AJAX allows you to work with existing codebases that heavily rely on XMLHttpReqeust or third-party AJAX libraries.

Consider factors such as browser support, project requirements, and developer familiarity

1. Browser support is a crucial factor to consider when deciding between Fetch API and AJAX.
   
   
2. If you need to support older browsers, AJAX may be the better choice.
   
   
3. Project requirements also play a significant role.
   
   
4. If you have complex data formats or require more control over the request process, AJAX might be the right tool.
   
   
5. Developer familiarity and expertise should also be considered.
   
   
6. If your team is experienced with AJAX and has existing codebases, sticking with it might streamline development.
   
   
7. It’s important to weigh all these factors and make an informed decision based on the unique needs of your project.

Most importantly, both Fetch API and AJAX have their strengths and weaknesses, and choosing between them depends on various factors.

Fetch API is recommended for new projects and modern browsers, thanks to its simplicity and powerful features.

On the other hand, AJAX might be more suitable for legacy systems or environments with limited browser compatibility.

Consider the browser support, project requirements, and developer familiarity before deciding which method to use.

By making the right choice, you can ensure efficient and reliable asynchronous HTTP requests in your web applications.

Read: What Makes Code with Mosh Stand Out from Free Resources?

Conclusion

Recapping the differences, Fetch API is a modern, standardized way to make HTTP requests, while AJAX is a traditional technique using the XMLHttpRequest object.

Understanding the key differences between Fetch API and AJAX is crucial for choosing the appropriate technology for web development.

Fetch API offers a more intuitive and cleaner syntax, with native support for promises, async/await, and better error handling.

On the other hand, AJAX provides more browser compatibility as it has been around longer and is widely supported.

It is essential to weigh the trade-offs between compatibility and modern features when deciding which approach to use.

To stay up-to-date with the latest web technologies, further exploration and experimentation with both Fetch API and AJAX are highly encouraged.

By gaining hands-on experience with both technologies, developers can better understand their strengths and weaknesses and make informed choices for their projects.

In closing, whether you decide to use Fetch API or AJAX, knowing the differences will empower you to make the most suitable selection for your web development needs.