It only fails when the code actually runs

To write reusable code that works with multiple types while keeping type safety

To convert JavaScript into TypeScript automatically

A type with only properties a and b from T

A type with every property of T except a and b

Every property key is a string and every value must be a number

Only one property named 'player' is allowed

The interface can only ever have numeric keys

A mapped type that makes all properties read-only

The function returns a promise that resolves with no meaningful value

The function must return undefined synchronously

The promise settles (resolves or rejects)

The next line of synchronous code finishes

A function that returns a decorator, allowing it to be configured with arguments

A built-in decorator that creates new classes

A tool that converts decorators into plain functions

Because it never successfully returns control to the caller

Writing looser, more permissive type annotations

Catching more potential bugs through stricter type checking

Exactly two elements, both numbers, in that order

A tuple starting with a string followed by zero or more numbers

A tuple that must contain exactly one string and one number

Turns it into a readonly tuple of the literal values 1, 2, 3

A discriminated union with a shared literal tag property

It creates and initializes a private, non-reassignable class field automatically

It exposes the parameter as a public static member

It provides a full implementation shared by all subclasses

It declares a method signature that subclasses must implement

It prevents the class from ever being extended

An object type whose keys are strings and whose values are all numbers

It lets TypeScript confirm the method exists on that narrowed type before allowing the call

TypeScript Quiz