String type behavior in Typescript - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this string concatenation?

Consider the following TypeScript code snippet. What will be printed to the console?

Typescript

const a: string = 'Hello';
const b: string = 'World';
console.log(a + ' ' + b);

A "Hello World"

B "HelloWorld"

C "Hello+World"

D "Hello World!"

💡 Hint

Think about how the + operator works with strings.

The + operator concatenates strings. Adding a space between the two strings results in "Hello World".

❓ Predict Output

intermediate

What is the output of this template literal?

What will this TypeScript code print to the console?

Typescript

const name: string = 'Alice';
const age: number = 30;
console.log(`Name: ${name}, Age: ${age}`);

A "Name: Alice, Age: 30"

B "Name: ${name}, Age: ${age}"

C "Name: Alice, Age: "

D "Name: Alice Age: 30"

💡 Hint

Look at how template literals insert variables.

Template literals replace ${variable} with the variable's value inside the string.

❓ Predict Output

advanced

What is the output of this string indexing?

What will this TypeScript code print to the console?

Typescript

const str: string = 'TypeScript';
console.log(str[4]);

A "r"

B "S"

C undefined

D "c"

💡 Hint

Remember that string indexing starts at 0.

Index 4 in 'TypeScript' is the fifth character, which is 'c'.

❓ Predict Output

advanced

What error does this code raise?

What happens when you try to assign a number to a string variable in TypeScript?

Typescript

let greeting: string = 'Hi';
greeting = 123;

A No error, greeting becomes '123'.

B Type 'number' is not assignable to type 'string'.

C Runtime error: Cannot assign number to string.

D SyntaxError: Invalid assignment.

💡 Hint

TypeScript checks types at compile time.

TypeScript does not allow assigning a number to a variable declared as string, causing a compile-time error.

🧠 Conceptual

expert

How many characters are in this string?

Consider the string with Unicode characters: const s = '👩👩👧👦'; How many characters does s.length report in TypeScript?

A 7

B 1

C 11

D 4

💡 Hint

Think about how JavaScript counts characters in strings with emoji and zero-width joiners.

The string contains multiple Unicode code units including zero-width joiners, so length counts code units, not user-perceived characters.