TypeScript Financial Management & Budgeting 4

Question 1

You're implementing a financial report generator as a TypeScript class. Which keyword declares a method that subclasses MUST implement?

Accepted Answer

abstract

Answer

The `abstract` keyword on a method in an abstract class forces all concrete subclasses to provide their own implementation.

Question 2

A payroll TypeScript module exports `calculateGross` and `calculateNet`. To import ONLY `calculateNet` with a renamed alias `netPay`, the correct syntax is:

Accepted Answer

import { calculateNet: netPay } from './payroll'

Answer

Named import aliasing uses `{ originalName: alias }` syntax inside the import braces.

Question 3

Which TypeScript mapped type creates a version of `BudgetItem` where every property's type is wrapped in a `Promise`?

Accepted Answer

{ [K in keyof BudgetItem]: Promise<BudgetItem[K]> }

Answer

A mapped type iterates over all keys K of T and maps each value type to a new type, here wrapping each in `Promise<>`.

Question 4

In a TypeScript budget app, you use `as const` on an array of expense categories. What effect does this have?

Accepted Answer

Converts the array to a tuple with readonly literal types

Answer

`as const` narrows the type to a readonly tuple with exact literal types, rather than a mutable `string[]`.

Question 5

A TypeScript financial service uses dependency injection. The constructor accepts `logger: ILogger`. This pattern is beneficial because:

Accepted Answer

It allows any object matching ILogger to be injected, improving testability

Answer

Programming to interfaces decouples the service from concrete implementations, allowing mock loggers in tests and real ones in production.

TypeScript Practice Test

TypeScript Practice Test

TypeScript Financial Management & Budgeting 4