Use async check instead of the sync one

[inancgumus]

What?

We're replacing sync check of k6 with the async check utility function.

Along the way, I've also fixed some small issues I saw.

Why

Writing concise code can be difficult when using the k6 check function with async code since it doesn't support async APIs. A solution that we have suggested so far is to declare a temporary variable, wait for the value that is to be checked, and then check the result later. However, this approach can clutter the code with single-use declarations and unnecessary variable names, for example:

const checked = await p.locator('.checked').isChecked();

check(checked, {
    'checked': c => c,
});

To address this limitation, we've added a version of the check function to jslib.k6.io that makes working with async/await simpler. The check function is a drop-in replacement for the built-in check, with added support for async code. Any Promises will be awaited, and the result is reported once the operation has been completed:

// Import the new check function from jslib.k6.io/k6-utils
import { check } from 'https://jslib.k6.io/k6-utils/1.5.0/index.js';

// ...

// Use the new check function with async code
check(page, {
    'checked': async p => p.locator('.checked').isChecked(),
});

Related PR(s)/Issue(s)

Closes #1725

Checklist

• I have used a meaningful title for the PR.
• I have described the changes I've made in the "What?" section above.
• I have performed a self-review of my changes.
• I have run the npm start command locally and verified that the changes look good.

• I have made my changes in the docs/sources/next folder of the documentation.
• I have reflected my changes in the docs/sources/v{most_recent_release} folder of the documentation.

[heitortsergent]

The changes look good to me, I'll wait until someone else on the development team takes a look. 🤓

Also, good catch on the k6/x/browser import. I did a search and found a few more instances of it (throttlenetwork.md, on.md, waitforevent.md). Do you mind if I make a commit to fix those as well?

[inancgumus]

@heitortsergent Thanks for your review!

The changes look good to me, I'll wait until someone else on the development team takes a look. 🤓

❤️ Of course!

Also, good catch on the k6/x/browser import. I did a search and found a few more instances of it (throttlenetwork.md, on.md, waitforevent.md). Do you mind if I make a commit to fix those as well?

Sure, please feel free :) Just for heads-up, anything above k6 0.52 must have k6/browser, whereas anything below must have k6/experimental/browser.

[inancgumus]

@heitortsergent In addition to your commit, I've also added another that fixes the ones in v51 and below.

[ankur22]

Thanks for this change 😄

Left some suggestions that might need to be looked at.

[inancgumus]

@ankur22 Thanks for your review! I've made the updates 👍