https://github.com/viendinhcom/supermemo
A JavaScript and TypeScript implementation of SuperMemo 2, a spaced repetition algorithm for flashcards.
https://github.com/viendinhcom/supermemo
deno flashcards javascript nodejs sm2 spaced-repetition supermemo supermemo2 typescript webpack
Last synced: 27 days ago
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A JavaScript and TypeScript implementation of SuperMemo 2, a spaced repetition algorithm for flashcards.
- Host: GitHub
- URL: https://github.com/viendinhcom/supermemo
- Owner: VienDinhCom
- License: mit
- Created: 2020-07-10T08:07:49.000Z (almost 5 years ago)
- Default Branch: master
- Last Pushed: 2025-03-28T05:23:41.000Z (about 1 month ago)
- Last Synced: 2025-04-14T18:17:20.600Z (27 days ago)
- Topics: deno, flashcards, javascript, nodejs, sm2, spaced-repetition, supermemo, supermemo2, typescript, webpack
- Language: TypeScript
- Homepage: https://jsr.io/@vien/supermemo
- Size: 416 KB
- Stars: 307
- Watchers: 2
- Forks: 25
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# SuperMemo
A JavaScript/TypeScript implementation of the [SuperMemo 2](https://super-memory.com/english/ol/sm2.htm) (SM2) algorithm for spaced based repetition flashcards.
[](https://www.npmjs.com/package/supermemo)
[](https://jsr.io/@vien/supermemo)
[](https://github.com/VienDinhCom/supermemo)
[](https://github.com/VienDinhCom/supermemo)
## Explanation
```ts
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 `repetition` value should be `0`.
- **interval**: inter-repetition interval after the repetitions (in days). The initial `interval` value should be `0`.
- **efactor**: easiness factor reflecting the easiness of memorizing and retaining a given item in memory. The initial `efactor` value should be `2.5`.
- **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.
If you like this project, hit the STAR button to bookmark it ⭐️
## Installation
### For Browser
```ts
import { supermemo } from 'https://esm.sh/supermemo@2';
```
### For Node
```
npm install --save supermemo
```
#### CommonJS
```js
const { supermemo } = require('supermemo');
```
#### ES Modules
```ts
import { supermemo, SuperMemoItem, SuperMemoGrade } from 'supermemo';
```
### For Deno
```
deno add jsr:@vien/supermemo
```
```ts
import { supermemo, SuperMemoItem, SuperMemoGrade } from '@vien/supermemo';
```
OR
```ts
import { supermemo, SuperMemoItem, SuperMemoGrade } from 'jsr:@vien/supermemo';
```
## Usage
```ts
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?
```ts
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);
```
## Experience
I work remotely, so improving my English is a constant challenge. I needed a way to expand my vocabulary and actually remember it.
That’s when I found the SuperMemo algorithm. It made sense. Spaced repetition helps lock words into long-term memory. So, I built this JavaScript/TypeScript library from the original Delphi code.
Then, I took it further—created a side project using React.js, Next.js and Hasura GraphQL. I used it to practice common words. Over time, I memorized more than 10,000 words. It worked.
After seeing the results, I turned it into a product to help others do the same. But it failed. Maybe I wasn’t good at marketing. Maybe most learners don’t have the patience I did.
Still, I learned something: a good method isn’t enough. People need the right mindset, too. Would I do it again? Probably. Because every failure teaches something new.
## References
- [The explanation of SuperMemo 2 Algorithm](https://super-memory.com/english/ol/sm2.htm)
- [The Delphi implementation of SuperMemo 2 Algorithm](https://super-memory.com/english/ol/sm2source.htm)