XMLHttpRequest vs Fetch: Which One Reigns Supreme in Modern Web Development?

In the ever-evolving landscape of web development, the ability to make asynchronous requests and fetch data from servers has become an indispensable part of building dynamic, interactive web applications. For years, the XMLHttpRequest (XHR) object has been the go-to tool for developers to achieve this functionality. However, with the introduction of the Fetch API, a new contender has entered the ring, promising a simpler and more modern approach to handling asynchronous requests. In this blog post, we'll dive deep into the battle between XMLHttpRequest and Fetch, exploring their strengths, weaknesses, and when to use one over the other.

The XML-What? Understanding XMLHttpRequest

Before we can fully appreciate the Fetch API, it's important to understand the tried-and-true XMLHttpRequest object. Despite its name, XMLHttpRequest has very little to do with XML these days; it's primarily used for making HTTP requests to retrieve data from servers, regardless of the data format (XML, JSON, text, etc.).

XMLHttpRequest has been around since the early days of web development and has played a crucial role in enabling technologies like AJAX (Asynchronous JavaScript and XML) and the rise of single-page applications (SPAs). While it has served us well, XMLHttpRequest can be verbose and cumbersome to work with, often requiring a significant amount of boilerplate code to handle different scenarios, such as checking the request status, handling errors, and parsing the response data.

Enter the Fetch API: A Modern, Streamlined Approach

The Fetch API was introduced as part of the ES6 (ECMAScript 2015) standard, with the goal of providing a more modern, simplified, and standards-compliant way of making asynchronous requests in JavaScript. Unlike XMLHttpRequest, which was initially developed as a browser-specific API, the Fetch API is a web standard, meaning it should work consistently across different browsers (with appropriate polyfills for older browsers).

One of the key advantages of the Fetch API is its promise-based approach. Instead of dealing with event-based callbacks like in XMLHttpRequest, the Fetch API returns a Promise, allowing developers to chain subsequent operations using .then() and .catch() methods. This results in cleaner, more readable code and better error handling capabilities.

How to Use the Fetch APIs in React?

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Apidog BlogDavid Demir

Simplicity and Readability: The Fetch API Advantage

When it comes to simplicity and readability, the Fetch API has a clear advantage over XMLHttpRequest. Consider the following examples:

XMLHttpRequest:

const xhr = new XMLHttpRequest();
xhr.open('GET', 'https://api.example.com/data');
xhr.onload = function() {
  if (xhr.status === 200) {
    const data = JSON.parse(xhr.responseText);
    // Do something with the data
  } else {
    // Handle error
  }
};
xhr.onerror = function() {
  // Handle error
};
xhr.send();

Fetch API:

fetch('https://api.example.com/data')
  .then(response => {
    if (response.ok) {
      return response.json();
    } else {
      throw new Error('Network response was not ok.');
    }
  })
  .then(data => {
    // Do something with the data
  })
  .catch(error => {
    // Handle error
  });

As you can see, the Fetch API code is more concise, easier to read, and follows a more linear flow using Promises. This can lead to improved code maintainability and a smoother development experience, especially for developers familiar with modern JavaScript syntax and patterns.

Handling Errors and Aborting Requests with XMLHttpRequest and Fetch API

Error handling is another area where the Fetch API shines. With XMLHttpRequest, handling errors can be a bit convoluted, as you need to rely on various events and status codes to determine if an error occurred and how to handle it. The Fetch API, on the other hand, provides a more streamlined approach to error handling through its Promise rejection mechanism.

Additionally, the Fetch API introduces the ability to abort requests, which was not possible with XMLHttpRequest. This can be particularly useful in scenarios where you need to cancel a long-running request, such as when the user navigates away from the page or when certain conditions are met.

Browser Support and Polyfills

While the Fetch API is a modern web standard, it's important to note that it may not be supported in older browsers. However, this issue can be easily addressed by using polyfills or transpiling your code with tools like Babel.

For XMLHttpRequest, browser support is generally not a concern, as it has been around for a long time and is supported in all modern browsers. However, keep in mind that certain features or behaviors of XMLHttpRequest may differ slightly across different browser versions and implementations.

When to Use XMLHttpRequest vs Fetch API

So, when should you use XMLHttpRequest, and when should you opt for the Fetch API? Here are some general guidelines:

Use XMLHttpRequest when:

• You need to support older browsers that don't have native support for the Fetch API, and you can't or don't want to use polyfills.
• You require advanced features or control over the request lifecycle that the Fetch API doesn't provide out of the box.
• You're working on an existing codebase that heavily relies on XMLHttpRequest, and refactoring to the Fetch API would be too disruptive.

Use the Fetch API when:

• You're building a modern web application and don't need to support older browsers or are willing to use polyfills.
• You value simplicity, readability, and a more modern approach to making asynchronous requests.
• You need to take advantage of features like aborting requests or better error handling capabilities.
• You're starting a new project and want to future-proof your codebase by using the latest web standards.

Generate XMLHttpRequest and Fetch code with Apidog

Apidog is an all-in-one collaborative API development platform that provides a comprehensive toolkit for designing, debugging, testing, publishing, and mocking APIs. Apidog enables you to automatically create XMLHttpRequest code for making HTTP requests.

Here's the process for using Apidog to generate XMLHttpRequest code:

Step 1: Open Apidog and select new request

Step 2: Enter the URL of the API endpoint you want to send a request to,input any headers or query string parameters you wish to include with the request, then click on the "Design" to switch to the design interface of Apidog.

Step 3: Select "Generate client code " to generate your code.

Step 4: Copy the generated code and paste it into your project.

Using Apidog to Send HTTP Requests

Apidog offers several advanced features that further enhance its ability to test HTTP requests. These features allow you to customize your requests and handle more complex scenarios effortlessly.

Step 1: Open Apidog and create a new request.

Step 2: Find or manually input the API details for the POST request you want to make.

Step 3: Fill in the required parameters and any data you want to include in the request body.

Conclusion

In the battle between XMLHttpRequest and the Fetch API, there is no clear winner or loser. Both have their strengths and weaknesses, and the choice ultimately depends on your specific project requirements and constraints.

That said, the Fetch API represents the future of asynchronous requests in web development. Its simplicity, promise-based approach, and adherence to modern web standards make it a compelling choice for developers building new applications or refactoring existing codebases.

However, it's important to remember that XMLHttpRequest has been a reliable workhorse for years and will likely remain relevant for some time, especially in legacy codebases or when supporting older browsers is a requirement.

Using  Apidog not only saves you valuable time and effort but also ensures that your code is accurate and error-free. With its user-friendly interface and intuitive features, Apidog is a must-have tool for any developer working with XMLHttpRequest and Fetch API.