SuperMemo
A JavaScript/TypeScript implementation of the SuperMemo 2 (SM2) algorithm for spaced based repetition flashcards.
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Explanation
type SuperMemoItem = {
interval: number;
repetition: number;
efactor: number;
};
type SuperMemoGrade = 0 | 1 | 2 | 3 | 4 | 5;
supermemo(item: SuperMemoItem, grade: SuperMemoGrade): SuperMemoItem- item
- repetition: the number of continous correct responses. The initial
repetitionvalue should be0. - interval: inter-repetition interval after the repetitions (in days). The initial
intervalvalue should be0. - efactor: easiness factor reflecting the easiness of memorizing and retaining a given item in memory. The initial
efactorvalue should be2.5.
- repetition: the number of continous correct responses. The initial
- grade:
- 5: perfect response.
- 4: correct response after a hesitation.
- 3: correct response recalled with serious difficulty.
- 2: incorrect response; where the correct one seemed easy to recall.
- 1: incorrect response; the correct one remembered.
- 0: complete blackout.
Installation
For Webpack
npm install --save supermemo
import { supermemo, SuperMemoItem, SuperMemoGrade } from 'supermemo';For Node
npm install --save supermemo
const { supermemo } = require('supermemo');For Deno
import { supermemo, SuperMemoItem, SuperMemoGrade } from 'https://deno.land/x/supermemo/mod.ts';Usage
let item: SuperMemoItem = {
interval: 0,
repetition: 0,
efactor: 2.5,
};
console.log(item);
item = supermemo(item, 5);
console.log(item);
item = supermemo(item, 4);
console.log(item);How to implement SuperMemo with DayJS?
import dayjs from 'dayjs';
import { supermemo, SuperMemoItem, SuperMemoGrade } from 'supermemo';
interface Flashcard extends SuperMemoItem {
front: string;
back: string;
dueDate: string;
}
function practice(flashcard: Flashcard, grade: SuperMemoGrade): Flashcard {
const { interval, repetition, efactor } = supermemo(flashcard, grade);
const dueDate = dayjs(Date.now()).add(interval, 'day').toISOString();
return { ...flashcard, interval, repetition, efactor, dueDate };
}
let flashcard: Flashcard = {
front: 'programer',
back: 'an organism that turns caffeine in software',
interval: 0,
repetition: 0,
efactor: 2.5,
dueDate: dayjs(Date.now()).toISOString(),
};
console.log(flashcard);
flashcard = practice(flashcard, 5);
console.log(flashcard);
flashcard = practice(flashcard, 3);
console.log(flashcard);