README.md

fsrs.js

fsrs.js is a JS Package that implements the Free Spaced Repetition Scheduler algorithm. It helps developers apply FSRS in their flashcard apps.

Transition to ts-fsrs

fsrs.js has provided basic features of FSRS. However, we recommend transitioning to ts-fsrs, another TypeScript implementation of the FSRS. Due to the heavy research work, the major maintainer of fsrs.js becomes busy and cannot maintain the project. ts-fsrs is more actively maintained and provides more features and documentation.

For migration support or inquiries, reach out via our issue tracker. We’re excited to continue our shared journey on ts-fsrs.

Getting Started

npm install fsrs.js

Usage

Create a card and review it at a given time:

const fsrsJs = require("fsrs.js")

let fsrs = new fsrsJs.FSRS();
let card = new fsrsJs.Card();
let rating= fsrsJs.Rating;
let state = fsrsJs.State;

//Set algorithm parameters
// fsrs.p.request_retention=0.9
// fsrs.p.maximum_interval=36500
// fsrs.p.w=[0.4, 0.6, 2.4, 5.8, 4.93, 0.94, 0.86, 0.01, 1.49, 0.14, 0.94, 2.18, 0.05, 0.34, 1.26, 0.29, 2.61]

console.log(fsrs.p)

let now = new Date(2022, 10, 29, 12, 30, 0, 0);
let scheduling_cards = fsrs.repeat(card, now);
console.log(scheduling_cards);

There are four ratings:

rating.Again //incorrect response
rating.Hard //recall; correct response recalled with serious difficulty
rating.Good //recall; correct response after a hesitation
rating.Easy // recall; perfect response

There are four states:

state.New //Never been studied
state.Learning //Been studied for the first time recently
state.Review //Graduate from learning state
state.Relearning //Forgotten in review state

//Get the new state of card for each rating:
scheduling_cards[rating.Again].card
scheduling_cards[rating.Hard].card
scheduling_cards[rating.Good].card
scheduling_cards[rating.Easy].card

//Update the card after rating `Good`:
card = scheduling_cards[rating.Good].card

//Get the due date for card:
due = card.due

//Get the state for card:
state = card.state

//Get the review log after rating `Good`:
review_log = scheduling_cards[rating.Good].review_log

License

Distributed under the MIT License. See LICENSE for more information.