withFeatureCheck() not fully chainable after withClientHints()?

[maoosi]

Library version

@ua-parser-js/pro-business - 2.0.6

Describe the bug

While implementing both withClientHints() and withFeatureCheck(), I noticed three things:

1/ API forces a two-step call

const parser = await UAParser(ua).withClientHints();
await parser.withFeatureCheck();

2/ Chaining works on Chrome but throws on Safari/Firefox (and maybe others?) with TypeError: ...withFeatureCheck is not a function.

3/ Docs only cover using withClientHints() or withFeatureCheck() separately but not together.

Expected behavior

Ideally, withFeatureCheck() should be chainable with withClientHints() and return graceful fallback values instead of throwing.

[faisalman]

Hi Sylvain,

Thanks for reporting this issue.

Currently withClientHints() and withFeatureCheck() must be called separately, but I agree that chaining them should be made possible.

In client-side, since withClientHints() returns an async result, chaining both methods must be done using then():

const chThenFeat = await UAParser().withClientHints().then(res => res.withFeatureCheck()));
const featThenCh = await UAParser().withFeatureCheck().then(res => res.withClientHints()));

Whereas in server-side, where withClientHints() returns synchronous result, chaining is expected to work directly:

const chThenFeat = UAParser().withClientHints().withFeatureCheck();
const featThenCh = UAParser().withFeatureCheck().withClientHints();

I'll add the fix to the pipeline and update the docs to make this clearer.

Thank you!