TypeScript Functions Quiz

This quiz tests your knowledge of functions in TypeScript, covering function types, call signatures, overloading, and type casting.

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Question 1

Which of the following is the correct way to declare a function type in TypeScript?

  • function sum(x: number, y: number): number;

  • let sum: (x: number, y: number) => number;

  • let sum: (x: number, y: number) -> number;

  • function sum(x: number, y: number) -> number;

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Question 2

What does the function keyword represent in TypeScript?

  • It defines a variable that can hold any value.

  • It creates a named function with parameters and return type.

  • It defines a class method.

  • It defines a constant value for a function expression.

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Question 3

Which of the following is the correct signature for a function that accepts two parameters of type string and returns a boolean?

  • (x: string): boolean

  • (x: boolean): string

  • (x: number, y: number): boolean

  • (x: string, y: string): boolean

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Question 4

What is function overloading in TypeScript?

  • Defining multiple functions with the same name but different implementations.

  • Defining one function that behaves differently depending on the number or type of arguments passed.

  • Allowing only one function signature for all functions.

  • Declaring a function with a fixed set of arguments.

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Question 5

In function overloading, which of the following is true?

  • A function can have multiple signatures, but only one implementation.

  • A function must have at least two implementations.

  • A function cannot have more than one return type.

  • Function overloading is not supported in TypeScript.

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Question 6

Which of the following correctly demonstrates function overloading in TypeScript?

  • Define multiple function signatures before a single implementation.

  • Define multiple functions with the same name and return type.

  • Use different function names for overloaded functions.

  • Define different return types for overloaded functions.

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Question 7

What is the result of the following TypeScript code?

JavaScript 
function add(x: number, y: number): number;
function add(x: string, y: string): string;
function add(x: any, y: any): any {
    return x + y;
}
console.log(add(5, 10));


  • 15

  • "510"

  • NaN

  • undefined

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Question 8

Which of the following is the correct way to cast a string to a number in TypeScript?

  • let num: number = <string> "42";

  • let num: number = "42" as number;

  • let num: number = Number("42");

  • let num: number = String("42");

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Question 9

How does type assertion work in TypeScript when casting?

  • It allows you to tell TypeScript to treat a variable as a more specific type.

  • It performs a runtime conversion of types.

  • It enforces the variable to always be of the asserted type.

  • It helps in creating custom type aliases.

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Question 10

Consider the following code in TypeScript. What is the result when the function sum() is called with two string arguments?

JavaScript 
function sum(a: number, b: number): number;
function sum(a: string, b: string): string;
function sum(a: any, b: any): any {
    return a + b;
}
console.log(sum("Hello", "World"));


  • HelloWorld

  • NaN

  • "Hello World"

  • undefined

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There are 10 questions to complete.

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