What is the purpose of max-age in Cache-Control headers when using request.headersArray() in Playwright?

Answer

To use request.headersArray() in @playwright/test, you should know that it returns an array of all request HTTP headers, with header names not lower-cased. Headers with multiple entries appear multiple times in the array.

Regarding max-age, it's an optional parameter in the Cache-Control header of an HTTP response, specifying how long a cached resource remains fresh. When a browser receives a response with a max-age value, it caches the resource for that duration before making another request.

For example, consider this Cache-Control header: "Cache-Control: max-age=3600". It means the resource can be cached for up to one hour (3600 seconds) before it's considered stale and needs revalidation through another server request.

Here's a TypeScript example using @playwright/test to intercept a request and log the headers array:

import { test, expect } from '@playwright/test';

test('Log request headers array', async ({ page }) => {
  // Intercept requests
  await page.route('**/*', (route, request) => {
    // Log the headers array
    console.log(request.headersArray());

    // Continue the request
    route.continue();
  });

  // Navigate to the website
  await page.goto('https://ray.run/');
});

In summary, request.headersArray() retrieves all headers associated with an HTTP request, while max-age is used in caching mechanisms to define how long resources should stay fresh before revalidation.