Create strongly typed array of arrays in TypeScript

Question

In a language like C# I can declare a list of lists like:

List<List<int>> list_of_lists;

Is there a similar way to declare a strongly typed array of arrays in TypeScript? I tried the following approaches but neither compiles.

var list_of_lists:int[][];
var list_of_lists:Array<int[]>;

Answer 1

int is not a type in TypeScript. You probably want to use number:

var listOfLists : number[][];

Answer 2

You do it exactly like in Java/C#, e.g. (in a class):

class SomeClass {
    public someVariable: Array<Array<AnyTypeYouWant>>;
}

Or as a standalone variable:

var someOtherVariable: Array<Array<AnyTypeYouWant>>;

Answer 3

The simplest is:

x: Array<Array<Any>>

And, if you need something more complex, you can do something like this:

y: Array<Array<{z:int, w:string, r:Time}>>

Answer 4

@Eugene you can use something like Array<Array<[string, number]>> to define a Map type

Answer 5

You can create your own custom types to create a strongly typed array:

type GridRow = GridCell[]   //array of cells
const grid: GridRow[] = []; //array of rows

Answer 6

It may look odd, but in TypeScript, you can create typed array of arrays, using the following syntax.

For example to create an array of numbers you could write the following:

const numbers: number[] = []; // or more verbose Array<number>

And to create an array of arrays of numbers, you could write the following:

const numbers: number[][] = []; // or more verbose Array<Array<number>>