Moment.js Date Library

Moment.js is a free and open-source JavaScript date library for parsing, validating, manipulating, and formatting dates. Created by Tim Wood (timrwood) in 2011, Moment.js was the most popular JavaScript date library for nearly a decade, used by millions of projects including Twitter, LinkedIn, and Uber. While now in maintenance mode (the team recommends date-fns, Luxon, or Day.js for new projects), Moment.js remains widely used in legacy codebases. Key features: parsing: parse dates from strings, Unix timestamps, or JavaScript Date objects. moment('2024-01-15') creates a moment object. Supports multiple formats via moment(string, format). Validation: isValid() checks if a parsed date is valid. Formatting: format dates using token strings (format('YYYY-MM-DD HH:mm:ss')). Supports localized formats (format('LL') for long localized date). Arithmetic: add and subtract time units (add(7, 'days'), subtract(2, 'months')). Chaining supported (add(1, 'day').subtract(2, 'hours')). Comparison: isBefore, isAfter, isSame, isBetween, isSameOrBefore, isSameOrAfter for comparing dates. Durals: duration objects for representing lengths of time (moment.duration({ hours: 2, minutes: 30 })). Relative time: fromNow(), toNow(), from(), to() for human-readable relative times ('3 hours ago', 'in 2 days'). Time zones: moment-timezone addon with full IANA timezone database for timezone conversion. Localization: 120+ language locales. Calendar time: calendar() for context-aware date display. UTC: full UTC support with moment.utc(). Plugins: extensive plugin ecosystem. JavaScript. MIT.