📦 Product Autocomplete Backend

A simple Node.js + Express backend that provides autocomplete search functionality on a list of products stored in a local JSON file (seeded from DummyJSON API).

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🚀 Features

• 🔍 /products/search endpoint with query support, pagination, and relevance scoring
• 🧠 Search ranking based on:
  1. Title starts with query → score 3
  2. Title includes query → score 2
  3. Brand includes query → score 1
• 🛠 Uses a local JSON file as a lightweight data store (no external DB)
• 📄 Written in TypeScript for type safety
• ✅ Includes Jest test coverage for core functionality
• 📦 Auto-fetches & seeds 100+ products on first run, skips if data exists

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🧪 Setup Instructions

# 1. Clone the repo
git clone https://github.com/Shubh6665/product-autocomplete-backend.git
cd product-autocomplete-backend

# 2. Install dependencies
npm install

# 3. Start the development server
npm start

The server will start on: http://localhost:3000

📝 On first run, the app automatically fetches products from DummyJSON and saves them to data/products.json.

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🧠 Approach & Thought Process

• Uses data/products.json to simulate a database.
• Matches queries against title and brand , ranking results by relevance
• Pagination support is built-in using limit and skip query parameters.
• Input validation ensures only meaningful queries (≥2 characters) are processed.

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🔬 Sample API Usage

Request:

GET /products/search?q=red&limit=5&skip=0

Curl example:

curl "http://localhost:3000/products/search?q=red&limit=5&skip=0"

Sample response:

{
  "count": 5,
  "results": [
    {
      "id": 4,
      "title": "Red Lipstick",
      "brand": "Chic Cosmetics",
      "category": "beauty",
      "price": 12.99,
      "score": 3
    },
    ...
  ]
}

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❗ Constraints & Validations

• Query parameter q is required and must be at least 2 characters long.
• Returns HTTP 400 Bad Request if validation fails.
• Returns an empty result array if no matches are found.

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🧪 Running Tests

To run the existing Jest tests, simply execute:

npm test

Tests cover:

• Valid search queries
• Case-insensitivity
• Pagination logic (limit and skip)
• Handling of invalid or too-short queries
• No-match scenarios

Run npm test -- --coverage for coverage report.

Sample output:

--------------------|---------|----------|---------|---------|-------------------
File                | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
--------------------|---------|----------|---------|---------|-------------------
All files           |   95.23 |    78.57 |     100 |     100 |                   
 productServices.ts |   95.23 |    78.57 |     100 |     100 | 8,16,22           
--------------------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests:       5 passed, 5 total
Snapshots:   0 total
Time:        0.708 s, estimated 1 s

📁 Project Folder Structure

product-autocomplete-backend/
│ 
├── src/
│   ├── controllers/
│   │   └── productController.ts
│   ├── data/
│   │   └── products.json 
│   ├── services/
│   │   └── productServices.ts    
│   ├── routes/
│   │   └── productRoutes.ts
│   ├── utils/
│   │   └── fetchandseed.ts                
│   └── index.ts                  
│
├── tests/
│   └── productServices.test.ts  
│
├── package.json
├── tsconfig.json
├── jest.config.js
└── README.md

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