How to declare an array of objects of different types in TypeScript?

Question

I have a an array with elements representing a HTML form of types TextInput, DateInput, Checkbox and so on.

How do I declare a variable type as an array of elements that can be any of these types?

Something like this

(TextInput | DateInput | Checkbox)[]

Answer 1

You can do:

let myArray: Array<TextInput | DateInput | Checkbox> = [];

And you can also do:

type MyArrayTypes = TextInput | DateInput | Checkbox;
let myArray: MyArrayTypes[] = [];

These two ways of defining arrays are equeivalent:

let a: number[] = [];
// is just like:
let b: Array<number> = [];

But sometimes the 2nd way fits better, like in your case.