How to perform string interpolation to TypeScript type?

String interpolation, also known as template literals are an extremely powerful tool in the JavaScript and TypeScript ecosystem.

`${`Hello`} ${`World`}` // Hello World

Can we do string interpolation when defining a type in TypeScript? The answer is yes!

Let me show you an example:

type PenguinsMembers = `${'Moose' | 'Ricky' | 'Blue'} ${`Penguin`}`
// "Moose Penguin" | "Ricky Penguin" | "Blue Penguin"

As you can see in the code example above, we created 3 potential values by using string interpolation for our type PenguinsMembers.

How to convert array of strings to TypeScript types

Let’s say you have an array of strings, and you want to convert each name to a potential type value. How would that been done?

We can use string interpolation to make that happen!

Let’s look at a code example:

const Penguins = [
] as const;

type PersonMembers = `${typeof Penguins[number]} Penguin`;
// "Moose Penguin" | "Ricky Penguin" | "Blue Penguin"

With string interpolation you can see that we’re grabbing each value from the array, and converting it into a TypeScript type.

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