Initial commit

Author: zachleat

.gitignore

@@ -0,0 +1 @@
+node_modules

README.md

@@ -0,0 +1,56 @@
+# Eleventy’s ISO8601 Date parser
+
+Features:
+
+- Zero dependency super minimal ISO8601 date parsing library. Alternatives were [too lax, inaccurate, huge on disk, or hundle in bundle](https://fediverse.zachleat.com/@zachleat/114870836413532617).
+- Dates with 8 digits do not require `-` delimiters (all other dates require delimiters, e.g. `YYYY-MM`)
+- Times with 6 digits do not require `:` delimiters (all others times require delimiters, e.g. `HH:II`)
+- Requires the `T` delimiter for date and time
+- Defaults to UTC when time zone is unknown instead of local time (`Z` can be explicit or implied)
+  - This matches previous behavior in Eleventy and this feature maintains consistency between build and deploy servers.
+- Supports +00:00 or -00:00 style time zone offsets
+- Invalid strings throw errors.
+
+Not supported:
+
+- Standalone times are not supported (must be date or datetime)
+- [ISO week date syntax](https://en.wikipedia.org/wiki/ISO_week_date) (e.g. `YYYY-W01-1`)
+- Day of year syntax is not supported (e.g. `YYYY-001`, `YYYY-365`)
+- Fractional syntax for hours or minutes (e.g. `T14.6` or `T10:30.6`). Fractional seconds (e.g. milliseconds) are supported (of course).
+
+## `luxon` Comparison
+
+More strict parsing compared with [Luxon’s `fromISO`](https://moment.github.io/luxon/#/parsing?id=iso-8601) (used in Eleventy v0.x through v3):
+
+```
+2016
+2016-05
+201605                    # Dropped, delimiter required if date is not 8 digits
+2016-05-25
+20160525
+2016-05-25T09
+2016-05-25T09:24
+2016-05-25T09:24:15
+2016-05-25T09:24:15.123
+2016-05-25T0924
+2016-05-25T092415
+2016-05-25T092415.123
+2016-05-25T09:24:15,123
+
+# No ISO week date syntax
+2016-W21-3                # Dropped
+2016W213                  # Dropped
+2016-W21-3T09:24:15.123   # Dropped
+2016W213T09:24:15.123     # Dropped
+
+# No day of year syntax (e.g. 200th day of the year)
+2016-200                  # Dropped
+2016200                   # Dropped
+2016-200T09:24:15.123     # Dropped
+
+# No implied current day (time-only syntax)
+09:24                     # Dropped
+09:24:15                  # Dropped
+09:24:15.123              # Dropped
+09:24:15,123              # Dropped
+```