Skip to content


Switch branches/tags

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time

Welcome to moment-guess 👋

Version Documentation Maintenance License: MIT

🎉 A utility package for guessing date's format 🙌


👨‍💻 Usage


# output default format
npx moment-guess --date "Fri, January 30th 2020, 10:00 AM"

# output strftime format
npx moment-guess --date "31st Dec, 2020" --format strftime

For details, try npx moment-guess --help

📝 Note: The above commands DO NOT INSTALL the package system-wide, npx is just a package runner.

📦 Package

npm install moment-guess
const guessFormat = require('moment-guess');

// default format
console.log(guessFormat("31/12/2020")); // DD/MM/YYYY

// default format
console.log(guessFormat("01/01/2020 10:00 AM PST", "default")); // [ 'DD/MM/YYYY hh:mm A z', 'MM/DD/YYYY hh:mm A z' ]

// strftime format
console.log(guessFormat("Fri, January 30th 2020, 10:00 AM", "strftime")); // %a, %B %o %Y, %I:%M %p

// Errors!
try {
	console.log(guessFormat("Invalid date!"));
} catch (err) {
	console.log(err.message); // Couldn't parse date

try {
	console.log(guessFormat("Mo, 23rd Nov, 2020", "strftime"));
} catch(err) {
	console.log(err.message); // Couldn't find strftime modifier for "Mo"

🙌 Supported Date Formats

  • 2020-07-24T17:09:03+00:00(IS0 8601)

  • Mon, 06 Mar 2017 21:22:23 +0000(RFC 2822)

  • 31/12/2020, 1.1.2020, 31-12-20(slash, dot or dash delimited dates, both US and UK styles)

  • 31-Dec-2020, 1-Jan-20(dash delimited with month name)

  • Fri, January 30th 2020, 10:00 AM(dow, dd Mon yyyy[, hh:mm:ss am|pm|AM|PM] with both short and long names)

🤷‍♀️ What happens in case of ambiguous input?

If the input is ambiguous like 01/01/2020(could mean DD/MM/YYYY or MM/DD/YYYY), it would display all possible matched formats. Try npx -q moment-guess -d "01/01/2020"

🤔 Motivation

PM: Hey, could you please display date on the rightmost part of the row in a format similar to Fri, 6th March 2020, 10:00 AM?

Me: Sure. (types on screen ... moment(timestampFromDB).format(// Uh Oh!, what should I put here?))

Methinks: Hmm...such requirements pop up once in a while, not everyday(at least for me). And everytime it happens, I end up sifting through momentjs docs here to choose the right format tokens in order to display date in the desired format("ddd, Do MMMM YYYY, hh:mm A" in this case). Can this be avoided? Is it possible to guess a date's format from the desired date value itself?

🔨 Run tests

npm run test

🔍 How does it work?

Entire module is split up into three main components, parsers, refiners and assigners.

  • Parsers break the input into individual tokens, giving meaning to each token(whether it's year, month, day...).

  • Refiners refine the parsed results based on certain chosen heuristics in case the input matched multiple parsers.

  • Assigners assign the appropriate format tokens(don't confuse these with generated tokens from input) enlisted here to each corresponding token based on the meaning given to the token by the parser(example, YYYY for a four digit year token).

👨 Author

Apoorv Mishra

🤝 Contributing

Contributions, issues and feature requests are welcome!
Feel free to check issues page.

Show your support

Give a ⭐️ if this project helped you!

📝 License

Copyright © 2020 Apoorv Mishra.
This project is MIT licensed.

This README was generated with ❤️ by readme-md-generator


🎉 A utility package for guessing date's format 🙌







No packages published