Learn React with TypeScript 3

Generic classes

We can make a whole class generic. Let's dive into an example of a generic class that stores data in a list:

1. Let's define our class first without any content:

class List<T> {}

We mark the class as generic by putting <T> after the class name.

2. Inside the class, let's create a private property for the data in the list:

private data: T[] = [];

We refer to the generic type using T. In our example, our data property is an array of whatever type the class has been declared with.

3. Let's now add a public method to get all the data in the list:

public getList(): T[] {  return this.data;}

We reference the generic array as the return type with T[].

4. Let's implement a method for adding an item to the list:

public add(item: T) { this.data.push(item); ...