Diff between fetch and xhr type: In the world of web development, making asynchronous requests to retrieve data from a server is a fundamental task. Two of the most commonly used methods for this purpose are Fetch API and XMLHttpRequest (XHR). Despite their similar objectives, there are significant differences between these two approaches that developers should be aware of.
Fetch API is a modern, promise-based approach to making HTTP requests in JavaScript. It provides a more straightforward and powerful way to handle network requests compared to the traditional XHR. One of the primary differences between fetch and xhr type is the syntax. Fetch uses a more intuitive and readable syntax, making it easier to understand and maintain. For example, to make a GET request using fetch, you would write:
“`javascript
fetch(‘https://api.example.com/data’)
.then(response => response.json())
.then(data => console.log(data))
.catch(error => console.error(‘Error:’, error));
“`
In contrast, making the same request using XHR would require more boilerplate code:
“`javascript
var xhr = new XMLHttpRequest();
xhr.open(‘GET’, ‘https://api.example.com/data’, true);
xhr.onreadystatechange = function() {
if (xhr.readyState === 4 && xhr.status === 200) {
console.log(JSON.parse(xhr.responseText));
}
};
xhr.onerror = function() {
console.error(‘Error:’, xhr.statusText);
};
xhr.send();
“`
Another significant difference between fetch and xhr type is the error handling. Fetch uses a more consistent and straightforward error handling mechanism based on promises. When an error occurs during the request, the catch block is executed, allowing developers to handle errors in a uniform manner. XHR, on the other hand, requires separate event listeners for onerror and onreadystatechange events to handle errors and request completion, respectively.
Moreover, fetch automatically handles HTTP errors and throws a rejected promise when the response status is not in the range 200-299. This makes it easier to handle errors and continue with the execution of the code. In contrast, XHR requires manual checks for the response status code to determine if an error occurred.
Fetch also supports more advanced features like redirects, caching, and CORS (Cross-Origin Resource Sharing) out of the box. XHR, while capable of handling these features, requires additional configuration and setup. For instance, to enable CORS in XHR, you would need to set the appropriate headers manually.
In conclusion, the diff between fetch and xhr type lies in their syntax, error handling, and feature support. While XHR has been the traditional choice for making HTTP requests, the Fetch API offers a more modern, readable, and feature-rich approach. As web development continues to evolve, it is essential for developers to be aware of these differences and choose the appropriate method based on their project requirements.
