Custom HTTP Headers

1. Introduction

HTTP headers are key-value pairs sent in an HTTP request or response that provide essential information about the request or the response. Custom HTTP headers allow developers to include additional information not defined in the original HTTP specification.

2. Definition

Custom HTTP Headers are user-defined headers that can be added to HTTP requests and responses to convey specific data needed by the server or client. They follow the same syntax as standard HTTP headers.

3. Usage

Custom headers can be used for various purposes such as:

• Providing authentication tokens.
• Specifying application-specific data.
• Controlling caching behavior.

4. Examples

4.1 Adding a Custom Header to a Request

const request = new XMLHttpRequest();
request.open('GET', 'https://api.example.com/data');
request.setRequestHeader('X-Custom-Header', 'MyValue');
request.send();

4.2 Reading a Custom Header from a Response

fetch('https://api.example.com/data')
    .then(response => {
        const customHeader = response.headers.get('X-Custom-Header');
        console.log(customHeader);
    });

5. Best Practices

When using custom HTTP headers, consider the following best practices:

• Use a prefix (e.g., X-) to avoid naming collisions with standard headers.
• Document the purpose and expected values of custom headers.
• Limit the use of custom headers to essential information only.

6. FAQ