This is a library for calculating the weeks of the Western Christian church calendar. This Christian calendar is also called the liturgical year. Each Sunday has a set of appointed readings called pericopes. The lectionary has pericopes as well as prayers, which together are the propers.

This library comes from I first build with friends while at college. It was first built to help my friends and I organize our dorm devotions. When the Lutheran Church Missouri Synod began work on a new hymnal we added it to the site. The hymnal committee put a Microsoft Word doc with the propers online for review. It included a revision of the one year lectionary and a new daily lectionary.

I am amazed that so many years later people still use the site. I open sourced the calculator used by the website in PHP before. This JavaScript library includes a similar calculator as well as calendar building tooling. It also includes structured data of the various propers. I hope that by open sourcing this library it will enable other to build new tools and applications.

All of the code in this repository is available free under the MIT license. Lectionary data belongs to the church at large throughout time.

This repository includes the calculator library and a React web app.

You can see the app in action at:

Install dependencies:

npm install

Run tests:

npm run test

Run the web app:

npm run start

The data in this repository was been entered by hand. If you spot an error, let me know or submit a pull request with the fix.

This repository is not intended to be an exhaustive set of Christian lectionaries. If you're interested in using this project with another tradition's lectionary that's great. However, it does not mean I will incorporate that lectionary into this repository. This codebase is reusable so that you can incorporate it in your own project.

Any functional change must include a thorough description, be linted and have tests.