Learn React with TypeScript 3

Tuple function parameters

Tuple function parameters in TypeScript 3 allow us to create strongly-typed rest parameters.

Time for an example:

1. When we first looked at rest parameters, we created a pure JavaScript version of logScores that collected an unlimited amount of arguments in a scores variable:

function logScores(...scores) {  console.log(scores);}

2. In TypeScript 3, we can now make this example strongly-typed with a tuple rest parameter. Let's give this a try in the TypeScript playground:

function logScores(...scores: [...number[]]) {  console.log(scores);}

3. Let's call our function with some scores:

logScores(50, 85, 75);

We don't get a compiler error, and if we run the program, we get an array containing 50, 85, 75 output in the console. ...