String enums in Typescript - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of accessing string enum member

What is the output of this TypeScript code?

Typescript

enum Direction {
  Up = "UP",
  Down = "DOWN",
  Left = "LEFT",
  Right = "RIGHT"
}

console.log(Direction.Left);

A "LEFT"

B Left

C 3

D undefined

💡 Hint

Remember that string enums store string values, not numbers.

The enum member Direction.Left is assigned the string "LEFT" explicitly, so logging it outputs "LEFT".

❓ Predict Output

intermediate

Value of enum member without explicit assignment

What will be the output of this TypeScript code?

Typescript

enum Status {
  Pending = "PENDING",
  Active,
  Completed = "COMPLETED"
}

console.log(Status.Active);

A 1

B "PENDING"

C undefined

D SyntaxError

💡 Hint

In string enums, all members must have string initializers.

In TypeScript, string enums require all members to have string values. Omitting the value for Active causes a syntax error.

🧠 Conceptual

advanced

Why use string enums over numeric enums?

Which of the following is the best reason to use string enums instead of numeric enums in TypeScript?

A String enums provide better readability and debugging because values are descriptive strings.

B String enums are faster to execute than numeric enums.

C String enums allow automatic reverse mapping from value to key.

D String enums consume less memory than numeric enums.

💡 Hint

Think about how values appear in logs and error messages.

String enums use descriptive string values which make code easier to read and debug compared to numeric enums which use numbers.

🔧 Debug

advanced

Identify the error in this string enum usage

What error will this TypeScript code produce?

Typescript

enum Colors {
  Red = "RED",
  Green = "GREEN",
  Blue = "BLUE"
}

const favorite: Colors = "RED";
console.log(favorite);

A No error, outputs "RED"

B ReferenceError: Colors is not defined

C Type '"RED"' is not assignable to type 'Colors'.

D TypeError: favorite is not a Colors enum

💡 Hint

Check the type compatibility between string literals and enum types.

You cannot assign a string literal directly to a variable typed as a string enum. The value must be Colors.Red.

🚀 Application

expert

Count enum members with string values

Given this string enum, how many members does it have?

Typescript

enum Fruits {
  Apple = "APPLE",
  Banana = "BANANA",
  Cherry = "CHERRY"
}

const count = Object.keys(Fruits).length;
console.log(count);

A 6

B 3

C 0

D undefined

💡 Hint

String enums do not create reverse mappings like numeric enums.

String enums only have keys for their members, so Object.keys returns the member names only, count is 3.