Default parameters with types in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a default value for the parameter name.

Typescript

function greet(name: string = [1]) {
  return `Hello, ${name}!`;
}

Drag options to blanks, or click blank then click option'

Anull

B"Guest"

Cundefined

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using null or undefined as default for a string parameter.

Not using quotes around the default string value.

The default value for name is set to the string "Guest". This means if no argument is passed, name will be "Guest".

2fill in blank

medium

Complete the function to set a default number parameter with type.

Typescript

function multiply(x: number, y: number = [1]): number {
  return x * y;
}

Drag options to blanks, or click blank then click option'

Anull

B"2"

C2

Dundefined

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string "2" instead of number 2.

Using null or undefined as default for a number parameter.

The default value for y is 2, a number matching the parameter type number.

3fill in blank

hard

Fix the error by completing the default parameter with the correct type.

Typescript

function setFlag(flag: boolean = [1]): string {
  return flag ? "On" : "Off";
}

Drag options to blanks, or click blank then click option'

Atrue

B"true"

C1

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Using string "true" instead of boolean true.

Using number 1 or null as default for boolean.

The default value for flag must be a boolean true, not a string or number.

4fill in blank

hard

Fill both blanks to create a function with a default string parameter and return type.

Typescript

function welcome(message: [1] = [2]): string {
  return message;
}

Drag options to blanks, or click blank then click option'

Astring

B"Hello"

Cnumber

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using number or boolean as type for a string parameter.

Not quoting the default string value.

The parameter message is typed as string with a default value "Hello". The function returns a string.

5fill in blank

hard

Fill all three blanks to define a function with a default boolean parameter and a typed return.

Typescript

function isActive(status: [1] = [2]): [3] {
  return status;
}

Drag options to blanks, or click blank then click option'

Astring

Btrue

Cboolean

D"active"

Attempts:

3 left

💡 Hint

Common Mistakes

Using string type or string default for boolean parameter.

Mismatching return type with parameter type.

The parameter status is typed as boolean with default true. The function returns a boolean.