Regex to Match Relative Date Expressions

This regex matches natural language relative date and time expressions. Here is the token-by-token breakdown:

(\d+) — Capturing group 1 matches one or more digits representing the quantity. This captures the numeric value like 5 in 5 minutes ago or 30 in 30 days from now.

\s+ — Matches one or more whitespace characters between the number and the time unit.

(second|minute|hour|day|week|month|year) — Capturing group 2 matches the time unit. The alternation provides seven common time units from the smallest (second) to the largest (year).

s? — Optionally matches a trailing s for plural forms. This allows both singular (1 day) and plural (5 days) units.

\s+ — Matches one or more whitespace characters between the unit and the direction.

(ago|from now|later|earlier) — Capturing group 3 matches the direction indicator. ago and earlier indicate past dates, while from now and later indicate future dates.

The g flag enables global matching and the i flag makes the match case-insensitive. This pattern captures three groups: the numeric quantity, the time unit, and the direction, providing all information needed to calculate the absolute date.

Relative date expressions are commonly used in user interfaces, log filtering, search queries, and natural language date parsing. Examples include: 5 minutes ago, 3 days from now, 2 weeks later, and 1 year earlier. This pattern is useful for chat applications, content timestamps, scheduling interfaces, and search tools that accept natural language date queries.