Why doesn't `fetch` throw an error on a 404?

The Fetch API was designed to only reject promises when the *network request itself* fails to complete (e.g., DNS lookup failure, offline). A 404 means the request completed successfully, and the server successfully told you the resource isn't there.

Do I always need to use `async/await` with fetch?

No, you can use `.then()` syntax. However, `async/await` is considered the modern standard because it avoids 'callback hell' and makes asynchronous code look and behave more like synchronous code, which is easier to read.

How do I send authentication tokens?

You include them in the `headers` object, typically using the Authorization header: `headers: { 'Authorization': 'Bearer YOUR_TOKEN' }`.

Why doesn't `fetch` throw an error on a 404?

The Fetch API was designed to only reject promises when the *network request itself* fails to complete (e.g., DNS lookup failure, offline). A 404 means the request completed successfully, and the server successfully told you the resource isn't there.

Do I always need to use `async/await` with fetch?

No, you can use `.then()` syntax. However, `async/await` is considered the modern standard because it avoids 'callback hell' and makes asynchronous code look and behave more like synchronous code, which is easier to read.

How do I send authentication tokens?

You include them in the `headers` object, typically using the Authorization header: `headers: { 'Authorization': 'Bearer YOUR_TOKEN' }`.

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JS Fetch API | JavaScript Tutorial

Learn about JS Fetch API in this comprehensive JavaScript tutorial for web development. Master the art of making network requests, handling JSON data streams, and managing server communication via GET and POST methods.

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Network Core

Communicating with remote servers via the Fetch API.

The Fetch API is the bridge between your local logic and remote data. It is the core of modern, dynamic web applications.

1The GET Request Lifecycle

Making a fetch() call starts an asynchronous network request. Because network speed is variable, fetch returns a Promise immediately. Once the server responds, you get a Response object. However, this object is just a stream of data. To actually work with it, you must use methods like .json() or .text(), which are *also* asynchronous. This two-step 'await' process is a common point of confusion but is essential for handling large data streams efficiently.

2The 'ok' Property Trap

A common mistake is assuming that fetch() will reject if the server returns an error code like 404 or 500. In reality, fetch() only rejects if there is a network failure (like being offline). If the server answers at all, the promise resolves. You must manually check the res.ok property (which is true if the status is in the 200-299 range) and throw your own error if the request failed from a business logic perspective.