[Feature] Add page.waitForRequest() and page.waitForResponse()

Hey!

After using Puppeteer for a little while now in a number of different scenarios (SSR, automated testing) a common piece of functionality that often came up as needed, or at very minimum a nice to have, was the ability to wait for a specific network request to be made, or alternatively for a specific network response to come back. As a result I propose the addition of the following two functions.

page.waitForRequest( match[, options])

• match <string> A regular expression to match against the request URL
• options <Object> Optional parameters
  • method <string|Array> Either a single HTTP request method (GET, POST, etc) as a string or an array of values ["GET", "POST"]. Defaults to all HTTP request methods.
  • timeout <number> Maximum time to wait in milliseconds

And additionally

page.waitForResponse( match[, options])

With a similar set of options. I’d probably also additionally add support for filtering by response code.

An example

await page.waitForRequest( 'https?://example.com/(users|companies)', { method: 'POST' });

Happy to submit a PR if you all think it’s a worthwhile addition!

Thanks!

[yanivefraim]

@aslushnikov - I started implementing this feature, and I have a questions regarding the api: Do we want to get an options object, with timeout, for example? (or is it enough to use default timeout)

[yanivefraim]

@matthaywardwebdesign - are you working on this? Can I help? (: