ITI vs Pure DI

Pure DI vs ITI

Business logic

With ITI and Pure DI your business logic stays exactly the same. There is no need to add any framework specific decorators or extends.

export interface Logger {
  info: (msg: string) => void
  warn: (msg: string) => void
  error: (msg: string) => void
}

export class ConsoleLogger implements Logger {
  info(msg: string): void {
    console.log("Console Logger:    ", msg)
  }
  warn(msg: string): void {}
  error(msg: string): void {}
}

export class PinoLogger implements Logger {
  info(msg: string): void {
    console.log("Pino Logger:    ", msg)
  }
  warn(msg: string): void {}
  error(msg: string): void {}
}

export class PaymentService {
  private readonly logger: Logger
  constructor(_logger: Logger) {
    this.logger = _logger
  }

  sendMoney() {
    this.logger.info("inversify logger info")
    return true
  }
}

Wiring

Pure DI:

./src/app.ts

const logger =
  process.env.NODE_ENV === "production" ? new PinoLogger() : new ConsoleLogger()

const paymentService = new PaymentService(logger)
paymentService.sendMoney()

ITI:

./src/app.ts

const root = createContainer()
  .add({
    logger: () =>
      process.env.NODE_ENV === "production"
        ? new PinoLogger()
        : new ConsoleLogger(),
  })
  .add((ctx) => ({
    paymentService: () => new PaymentService(ctx.logger),
  }))

const ps = root.items.paymentService
ps.sendMoney()