Learn React with TypeScript 3

JavaScript rest and spread syntax

In JavaScript, a rest parameter collects multiple arguments and condenses them into a single argument. It is called rest because it collects the rest of the arguments into a single argument.

A rest parameter has nothing to do with Representational state transfer protocol (REST).

This syntax was introduced in ES6 and allows us to nicely implement functions that have an indefinite number of parameters.

We define a rest parameter with three dots preceding the parameter name.

Let's go through a quick example:

1. Let's create a logScores function that takes in a scores rest parameter that just outputs the parameter to the console:

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

This is pure JavaScript - we'll ...