feat: Add timezone to events

[robbie-c]

Changes

Add timezone to events (timezone looks like Europe/London).

In older browsers that don't support Intl, this property won't be sent.

This is useful for a couple of things:

• I want to add a time of day query, which shows you how active your site is at different times of day, and it'd be cool to have a toggle to show it by the user's timezone (so you could see that e.g. around the world your app is always popular at 8am)
• I can use this for the cookieless rotating salt, to figure out which day's salt to use

Checklist

• Tests for new code (see advice on the tests we use)
• Accounted for the impact of any changes across different browsers
• Accounted for backwards compatibility of any changes (no breaking changes in posthog-js!)

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Name	Status	Preview	Updated (UTC)
posthog-js	✅ Ready (Inspect)	Visit Preview	Oct 29, 2024 7:25pm

[pauldambra]

this is great... IMHO the solution to passing dates around and knowing what's happening

[github-actions]

Size Change: +1.19 kB (+0.04%)

Total Size: 2.95 MB

Filename	Size	Change
dist/array.full.es5.js	249 kB	+122 B (+0.05%)
dist/array.full.js	335 kB	+119 B (+0.04%)
dist/array.full.no-external.js	334 kB	+119 B (+0.04%)
dist/array.js	166 kB	+119 B (+0.07%)
dist/array.no-external.js	165 kB	+119 B (+0.07%)
dist/main.js	167 kB	+119 B (+0.07%)
dist/module.full.js	335 kB	+119 B (+0.04%)
dist/module.full.no-external.js	334 kB	+119 B (+0.04%)
dist/module.js	166 kB	+119 B (+0.07%)
dist/module.no-external.js	165 kB	+119 B (+0.07%)

ℹ️ View Unchanged

Filename	Size
dist/all-external-dependencies.js	182 kB
dist/exception-autocapture.js	8.77 kB
dist/external-scripts-loader.js	2.19 kB
dist/recorder-v2.js	102 kB
dist/recorder.js	103 kB
dist/surveys-preview.js	56.7 kB
dist/surveys.js	62.1 kB
dist/tracing-headers.js	1.33 kB
dist/web-vitals.js	10.3 kB

_{compressed-size-action}

[marandaneto]

@robbie-c would be interesting to add $locale as well
did not test but something like:

function getBrowserLocale(): string | undefined {
    try {
        return navigator.language || navigator.languages[0];
    } catch {
        return undefined;
    }
}