Never write your own date parsing library

9 months ago

The author initially adopted Luxon as the date parsing library for Eleventy, which was a good choice at the time.
Luxon's large size (4.7 MB in node_modules, 229 kB in bundle) became a problem as Eleventy expanded to more JavaScript environments.
The author searched for alternatives but found issues with accuracy (dayjs failed 80 out of 228 tests).
The decision was made to tighten date parsing requirements, aligning with RFC 9557, which is compatible with the upcoming Temporal API.
A new library, @11ty/parse-date-strings, was created to replace Luxon, focusing on RFC 9557 compatibility and reducing bundle size significantly.
The new library saves ~230 kB in the bundle and reduces node_modules size from 21.3 MB to 16.6 MB.
Other alternatives like @js-temporal/polyfill and temporal-polyfill were also considered but not chosen for Eleventy's needs.

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