Fetch: Request headers

Being able to set the HTTP request header is essential, and fetch gives us the ability to do this using the Headers object:

const headers = new Headers()
headers.append('Content-Type', 'application/json')


const headers = new Headers({
  'Content-Type': 'application/json'

To attach the headers to the request, we use the Request object, and pass it to fetch() instead of passing the URL.

Instead of:


we do

const request = new Request('./file.json', {
  headers: new Headers({
    'Content-Type': 'application/json'

The Headers object is not limited to setting value, but we can also query it:


and we can delete a header that was previously set:


Lessons this unit:

0: Introduction
1: How to use Fetch
2: Catching errors in network requests
3: The Response object
4: Getting the body content
5: The Request object
6: ▶︎ Request headers
7: POST requests