TypeScript Risk Assessment & Management 2

Question 1

Which TypeScript compiler option helps catch potential null dereference risks at compile time?

Accepted Answer

strictNullChecks

Answer

strictNullChecks prevents assigning null or undefined to typed variables unless explicitly allowed, catching null dereference risks at compile time.

Question 2

A team inherits a large JavaScript codebase and must assess migration risk. Which TypeScript feature allows incremental adoption with the least disruption?

Accepted Answer

allowJs: true with gradual .ts conversion

Answer

allowJs lets TypeScript coexist with JavaScript files, enabling incremental migration without requiring a full rewrite upfront.

Question 3

What risk does the 'any' type introduce in a TypeScript codebase?

Accepted Answer

It bypasses type checking, allowing runtime errors to go undetected

Answer

The any type opts out of TypeScript's type system entirely, meaning type errors that would normally be caught at compile time can become runtime failures.

Question 4

When using third-party libraries without @types definitions, what is the safest risk mitigation strategy?

Accepted Answer

Write a custom .d.ts declaration file for the library

Answer

Writing a custom declaration file provides type safety coverage for untyped libraries without weakening the rest of the project's type settings.

Question 5

Which pattern reduces the risk of a discriminated union being handled incompletely at runtime?

Accepted Answer

Adding an exhaustiveness check with a never-typed default branch

Answer

Assigning the default branch to a never variable causes a compile error if a new union member is added but not handled, enforcing completeness.

TypeScript Practice Test

TypeScript Practice Test

TypeScript Risk Assessment & Management 2