Tuple Type in TypeScript

Vanilla JavaScript does not contain tuple data type. TypeScript brings Tuple Type.

What is Tuple?

It is an array with fixed length and fixed value. Example:

const role = [4, "teacher"];

Above array elements have a meaning. 4 is role id and "teacher" is role description. Any other array values like, [4, "teacher", true] is invalid.

We cannot create a tuple in vanilla JavaScript.

Defining a Tuple in TypeScript

Here is how we can set a tuple type using TypeScript.

let role: [number, string];

Above type says, role can have an array whose length should be 2. Also, the first element should be a number and second one a string.