Arrays and Tuples

Part of the TypeScript course

A single value is rarely enough. You have a list of temperatures, a list of names, a list of prices. And the moment you have a list, a new kind of mistake becomes available: the list that was supposed to hold numbers has a string in it, somewhere, put there by a function three files away, and you find out when an arithmetic operation quietly produces nonsense.

TypeScript's answer is to let you say what a list holds. Not just "this is a list", but "this is a list of numbers", and then it checks every value that goes in and every value that comes out. ...