Mini-App

A persistent CRUD app to manage items across sessions — built with full create, view, update, and delete support, persistent local storage, and a smart search/filter feature. Includes clean code, a one-command setup, and detailed ANSWERS.md covering stack decisions, edge cases, and AI usage.

Study Flashcards ✦

A beautiful, high-performance web application for creating flashcards and studying them using the SM-2 Spaced Repetition Algorithm. Built with a sleek dark glassmorphism design system, this application is optimized for visual excellence, responsiveness, and zero-dependency portability.

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Features

1. Decks Management (CRUD)

• Create, edit, and delete flashcard decks.
• Assign custom colors to decks for visual organization.
• View real-time statistics including total card count and active "due for review" counts.
• Cascade deletes — deleting a deck safely removes all its child cards.

2. Flashcards Management (CRUD)

• View a detailed list of all cards in a deck.
• Create, edit, and delete individual cards with distinct front (question) and back (answer) text.
• View real-time review intervals and ease factor metrics per card.

3. Spaced Repetition Study Mode (Beyond CRUD)

• 3D Card Flip: Double-sided cards featuring smooth 3D CSS transforms and glassmorphic blur.
• Recall Ratings: Self-assess recall using 4 ratings:
  • Again (0): Resets repetitions/intervals and decreases the ease factor. The card goes back to the end of the session queue so you can try it again.
  • Hard (1): schedules a short interval and decreases the ease factor slightly.
  • Good (2): normal interval increase.
  • Easy (3): large interval increase and increases the ease factor.
• Keyboard Navigation: Use keyboard shortcuts to speed up study sessions:
  • Space to flip the card and reveal the answer.
  • 1, 2, 3, 4 to submit ratings (Again, Hard, Good, Easy).
• Session Complete Screen: Shows summary analytics after completing reviews.

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Tech Stack

Layer	Technology	Purpose
Server	Node.js + Express.js	Lightweight web server serving static files and API endpoints.
Database	SQLite (via sql.js)	Zero-dependency, pure-JS SQLite compilation. Loads and saves the database file (flashcards.db) to disk synchronously on updates, making it highly portable across systems without requiring native C++ build tools.
Frontend	Vanilla HTML / CSS / JS	Multi-view single-page application (SPA) with hash-based routing (#/), custom CSS variables, and zero frontend framework dependencies.

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File Structure

d:\Mini App\
├── package.json        # Node dependency manifest
├── server.js           # Express app entry point
├── flashcards.db       # SQLite database file (auto-generated)
├── src/
│   ├── db.js           # SQL.js wrapper & schema initialization
│   ├── sr.js           # SM-2 Spaced Repetition implementation
│   └── routes/
│       ├── decks.js    # Deck management API endpoints
│       ├── cards.js    # Card management API endpoints
│       └── study.js    # Study session & rating submission endpoints
└── public/
    ├── index.html      # SPA entry page
    ├── css/
    │   └── style.css   # Dark glassmorphic stylesheet
    └── js/
        ├── app.js      # Hash-based SPA Router & Bootstrapper
        ├── api.js      # Central API Client
        ├── components/
        │   ├── modal.js   # Reusable overlays (deck/card editor, confirm)
        │   └── toast.js   # Notification toast popups
        └── views/
            ├── deckList.js   # Deck grid view
            ├── deckDetail.js # Card list & CRUD view
            └── studyMode.js  # Card study interface

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Getting Started

Prerequisites

• Node.js 18+ installed on your local machine.

Installation

1. Navigate to the project root directory:

   cd "d:\Mini App"

2. Install dependencies:

   npm install

Running the Application

Start the development server:

npm run dev

The application will boot and print:

  ✦ Study Flashcards running at http://localhost:3000

Open http://localhost:3000 in your browser to start studying!

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Spaced Repetition (SM-2 Algorithm) Details

This app implements the SuperMemo-2 (SM-2) algorithm. The next review interval is calculated using:

• Ease Factor (EF): Defaults to 2.5. It measures how easy the card is.
• Repetitions (n): The number of consecutive successful recalls.
• Interval (I): The number of days until the card is shown again.

Calculation Logic:

• If Again (0): Repetitions = 0, Interval = 0 days, Ease Factor = max(1.3, EF - 0.2).
• If Successful Recall (rating ≥ 1):
  • Repetitions = n + 1
  • If n == 0 (First review): Interval = 1 day
  • If n == 1 (Second review): Interval = 3 days
  • If n > 1 (Subsequent reviews): Interval = Interval * EF
  • Adjust EF: EF = max(1.3, EF + adjustment)
    • Hard (1): -0.15
    • Good (2): 0.00
    • Easy (3): +0.15
• The interval is capped at 365 days to ensure cards are reviewed at least once a year.