Introduction to Timing-Allow-Origin in HTTP Headers

When you act as a web developer, you may come across meanings that differ from the HTTP Headers. These headers allow browsers to manage request behaviors. One of these headers that may be less familiar is Timing-Allow-Origin. This header helps you specify which sources can receive timing-related information about a specific request.

Moreover, you may also be aware that web security is one of the critical issues that requires special attention. Timing-Allow-Origin provides you the capability to prevent sensitive timing information from being disclosed to unauthorized sources. Generally, when you perform a fetch operation, the browser, by default, retrieves timing-related information only for the domains that were included in the initial request, potentially restricting it. By using the Timing-Allow-Origin header, you can change this limitation.

Now let's see how to use this header in practice. Assume you have an API service that needs to get timing information back for specific domains in access. For this purpose, you should use Timing-Allow-Origin in the response headers.

It may be noted that the Timing-Allow-Origin header indicates the special condition of the response. The more the user needs precise control over the timing-related information operations of their network, such as for performance improvement or detailed analysis through specialized tools.

Example Code for Timing-Allow-Origin

HTTP/1.1 200 OK
Timing-Allow-Origin: *
Content-Type: application/json

{"message": "This is a response from the server"}

In this example, the HTTP request was sent to the server, and the server responded by adding the Timing-Allow-Origin header with a value of *. This means that the timing-related information of this response can be observed by anyone.

HTTP/1.1 200 OK
This line indicates the HTTP response status, which is 200 OK, meaning the request was successful.
Timing-Allow-Origin: *
By setting the asterisk in this section, it allows any domains to observe the timing-related information.
Content-Type: application/json
This line specifies the content type of the response, which is JSON here.
{"message": "This is a response from the server"}
This part contains the body of the server response presented in JSON format.