API is written using Node.js with Express using Typescript. express-validator is used for validating the requests.
Jest and Supertest is used for testing.
Pino is used for logging.
GET /quote
| Query parameter | Description |
|---|---|
| baseCurrency | String, 3 letters ISO currency code. Currency to convert from. |
| quoteCurrency | String, 3 letters ISO currency code. Currency to convert to. |
| baseAmount | Integer. The amount to convert in cents. Example: 100 (1 USD) |
API calculates the total amount expected in the quoteCurrency accordingly to the exchange rate provided by the 3rd party service.
Response body: JSON with the following properties
| Property | Description |
|---|---|
| exchangeRate | Decimal, the offered exchange rate. Up to 3 decimal digits. |
| quoteAmount | Integer, the expected amount in cents. Rounded with default Math.round() |
LRU Cache is used for caching exchange rates fetched from external API.
Cache size can be passed via environment variable LRU_CACHE_SIZE (defaults to 2).
LRU Cache is implemented as simple in-memory cache using Javascript Map type as it holds key-value pairs and remembers the original insertion order of the keys.
Exchange rates are fetched from https://exchangerate-api.com
npm run dev - runs application in development mode with reload on save
npm run start - transpiles Typescript to Javascript and runs application
Application tested with Node.js version v16.13.1.
Before running application run npm install.
npm run test - runs tests
| Variable | Description | Default |
|---|---|---|
| EXCHANGE_RATE_API | External Exchange Rate API URL | - |
| PORT | Port for application to use | 3000 |
| DEBUG_LOGS | Enables debug logging | false |
| LRU_CACHE_SIZE | LRU Cache size for caching exchange rates | 2 |
| LRU_CACHE_SIZE | LRU Cache size for caching exchange rates | 2 |
| SUPPORTED_CURRENCIES | List of currencies to be supported |
Environment variables are taken from the .env file using dotenv library.