Undefined TypeScript Interface

Here's my situation:

  public retrieveConnections() : IUser[] {
    let connections: IUser[];
    connections[0].Id = "test";
    connections[0].Email = "asdasd";

    return connections;
  }

I know this might be a dumb question, but why is connections[0] showing up as undefined? What should I do if I don't have a User type class in this scenario.

Answer №1

Let's break down this scenario:

let friends: IUser[];

This line of code declares a variable named friends with the type IUser[], but it is not yet initialized, so its value is currently undefined.

To initialize it as an empty array, you can do:

let friends: IUser[] = [];

Now that friends is an empty array, you need to add some content to it. First, create an instance of IUser:

// Here is one way to create an IUser object
let friend: IUser = {Id: "test", Email: "asdasd"};

Next, push this created user into the array:

friends.push(friend);

Your final code should look like this:

public getFriends(): IUser[] {
    let friends: IUser[] = [];

    let friend: IUser = {Id: "test", Email: "asdasd"};
    friends.push(friend);

    return friends;
}

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