TypeScript Financial Management & Budgeting 2

Question 1

In TypeScript, you have a `Budget` interface with optional fields. Which utility type creates a version where ALL fields are required?

Accepted Answer

Required<Budget>

Answer

`Required` maps all optional properties to required, the opposite of `Partial`.

Question 2

You're building a financial ledger in TypeScript. Which numeric type concern is most critical when dealing with currency calculations?

Accepted Answer

Floating-point precision errors with number

Answer

JavaScript/TypeScript `number` uses IEEE 754 floating-point, causing precision errors in currency math (e.g., 0.1 + 0.2 !== 0.3).

Question 3

A budget tracker stores `amount: string | number`. Which TypeScript pattern safely extracts only numeric amounts for calculation?

Accepted Answer

Type guard: typeof amount === 'number'

Answer

A type guard narrows the union type at runtime, ensuring only `number` values enter arithmetic operations.

Question 4

You need a TypeScript function that accepts a budget category and returns spending data. Which return type best models 'data or an error message'?

Accepted Answer

Result<SpendingData, string>

Answer

A `Result<T, E>` discriminated union explicitly models success/failure, making error handling type-safe and self-documenting.

Question 5

Which TypeScript feature allows you to enforce that budget category names must be one of a fixed set of string literals?

Accepted Answer

Enums or string literal union types

Answer

Enums and string literal unions (e.g., `'rent' | 'food' | 'utilities'`) restrict values to a predefined set at compile time.

TypeScript Practice Test