Add runtime regex check to prevent SyntaxError on older browsers#8353
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Add runtime regex check to prevent SyntaxError on older browsers#8353
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…n older browsers The UA-based isLookbehindSupported() can return true for unrecognized browsers (e.g. in-app WebViews, Chrome on old iOS using WebKit), causing highlight.ts to load highlightjs-roc which contains regex literals with lookbehind assertions. This triggers a fatal SyntaxError during module parsing on browsers that don't support lookbehinds. Adding areAllRegExpFeaturesSupported() as a runtime check before UA sniffing ensures the guard works correctly even when UA detection fails. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
SyntaxError: Invalid regular expression: invalid group specifier namereported on/journey(and likely other pages)isLookbehindSupported()function uses UA sniffing which can incorrectly returntruefor browsers that don't support lookbehinds (e.g. in-app WebViews, Chrome on old iOS using WebKit). This causeshighlight.tsto loadhighlightjs-roc, which contains regex literals with lookbehind assertions, triggering a fatal parse-timeSyntaxErrorareAllRegExpFeaturesSupported()runtime check (which was previously unused) as the first guard inisLookbehindSupported(), so even when UA detection fails the runtime check catches itTest plan
yarn testpasses (all failures are pre-existing@bugsnag/jsmodule resolution issues)areAllRegExpFeaturesSupported()returnsfalse→isLookbehindSupported()returnsfalse→lazyHighlightAll()exits early →highlight.tsnever loaded → no parse error🤖 Generated with Claude Code