9

18

23

21

14

A variable is declared with const and its value cannot be reassigned.

An expression can be replaced with its evaluated value without changing the overall behavior of the program.

A function has no side effects and always produces the same result for the same set of inputs.

A function that, instead of returning a result, passes the result to another function called a continuation.

An optimisation where a recursive function call in the final position is converted into a loop to prevent stack overflow.

The prototype chain

Dependency injection

A closure

Currying

Strict equality

const studentB: Student = { id: 456, name: "Bob" };

const studentD: Student = { name: "David", major: "Physics" };

const studentC: Student = { id: "789", name: "Charlie" };

const studentA: Student = { id: 123, name: "Alice", major: "CS", year: 3 };

const studentE: Student = { id: 321, name: "Eve", major: null };

To automatically add comparison logic (like < and >) to any custom object type T that is passed into the function.

To create a type alias that makes complex function signatures shorter and easier to read.

To allow a function to accept arguments of the `any` type, disabling all type checking for maximum flexibility.

To enable a function to work correctly on a union type, such as string | number.

To create a function that is both reusable for different data types and maintains type safety by ensuring type consistency.

(x, y, z) => x + y + z

x => { x * x * x }

x => x * 3

function(x) { x * x * x }

x => x * x * x

The variable `myObj` cannot be reassigned, but the properties of the object it references (like `myObj.a`) are mutable.

The `const` keyword is a direct alias for TypeScript's `Readonly` utility, making the object deeply immutable at compile time.

The `const` keyword has no effect on objects; both the variable `myObj` and its properties are fully mutable.

The variable `myObj` is mutable and can be reassigned, but its initial properties cannot be changed.

The variable `myObj` cannot be reassigned, and the properties of the object it references (like `myObj.a`) are also immutable.

[5, 6, 6]

3

18

None of the options is correct.

["apple", "banana", "cherry"]

The typeof operator.

A generic type parameter.

A union type.

An interface with an optional property.

A type alias.

It uses a gradual typing system to catch type-related errors during compile time, which would otherwise only be discovered at run time.

It provides a Readonly type that enforces deep immutability on objects at run time, preventing any modifications to their properties.

It fundamentally simplifies asynchronous programming, removing the need for callbacks or continuations.

It allows for the use of arrow functions and the const keyword, which are not available in JavaScript.

It introduces a build chain that transpiles code, making it run significantly faster in the browser than equivalent JavaScript code.