Generic array syntax in Typescript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the generic array syntax in TypeScript?

It is a way to define arrays with a specific type using angle brackets, like Array<Type>. For example, Array<number> means an array of numbers.

beginner

How do you declare an array of strings using generic array syntax?

You write <code>let names: Array&lt;string&gt; = ['Alice', 'Bob'];</code> which means <strong>names</strong> is an array that only holds strings.

beginner

What is the difference between string[] and Array<string> in TypeScript?

Both mean the same: an array of strings. string[] is shorthand, and Array<string> is the generic syntax. You can use either based on preference.

intermediate

Can you use generic array syntax with custom types?

Yes! For example, if you have a type Person, you can write Array<Person> to make an array of Person objects.

intermediate

Why use generic array syntax instead of the shorthand?

Generic syntax is clearer when working with complex types or nested generics. It helps readability and consistency in some cases.

Which of the following declares an array of numbers using generic array syntax?

A let nums: number<> = [1, 2, 3];

B let nums: number = [1, 2, 3];

C let nums: Array = [1, 2, 3];

D let nums: Array<number> = [1, 2, 3];

Option D correctly uses Array<number> to declare an array of numbers.

What does Array<string> mean in TypeScript?

A An array of strings

B A function returning a string

C A string variable

D An array that can hold any type

Array<string> means an array that holds only strings.

Which is the shorthand for Array<boolean>?

A boolean[]

B bool[]

C Array<boolean[]>

D boolean<>

boolean[] is the shorthand for Array<boolean>.

Can you use generic array syntax with a custom type Car?

A No, only built-in types work

B Only if Car is a string

C Yes, like <code>Array&lt;Car&gt;</code>

D Only with interfaces, not types

Generic array syntax works with any type, including custom types like Car.

Why might you choose Array<Type> over Type[]?

A It is required by TypeScript

B It is clearer with complex or nested types

C It is shorter to write

D It runs faster

Generic syntax can be clearer and easier to read with complex or nested types.

Explain how to declare an array of numbers using generic array syntax in TypeScript.

Think about how you tell TypeScript what type the array holds using < and >.

Describe the difference and similarity between string[] and Array<string>.

Both are ways to say 'array of strings' but look different.