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In this section, we will explore how to use TypeScript interfaces and types to enhance the robustness and readability of your Playwright tests. Understanding these concepts is crucial for writing maintainable and scalable test scripts.

Key Concepts

What are Interfaces and Types?

Interfaces: Define the shape of an object, specifying what properties and methods it should have.
Types: Can be used to define a variety of structures, including primitive types, union types, and more complex structures.

Differences Between Interfaces and Types

Feature	Interface	Type Alias
Declaration Merging	Supported	Not supported
Extending	Can extend other interfaces	Can extend other types using `&`
Use Cases	Best for defining object shapes	Best for complex type definitions

Practical Examples

Defining an Interface

An interface in TypeScript is used to define the structure of an object. Here's a simple example:

interface User {
  name: string;
  age: number;
  email: string;
}

const user: User = {
  name: "Alice",
  age: 30,
  email: "[email protected]"
};

Explanation:

The User interface defines an object with three properties: name, age, and email.
The user object is then created with the structure defined by the User interface.

Using Type Aliases

Type aliases can be used to create more complex types, such as union types:

type ID = number | string;

let userId: ID;
userId = 101; // valid
userId = "abc123"; // also valid

Explanation:

The ID type alias allows a variable to be either a number or a string.
This flexibility is useful when dealing with IDs that might come in different formats.

Extending Interfaces

Interfaces can be extended to create more specific types:

interface Person {
  name: string;
  age: number;
}

interface Employee extends Person {
  employeeId: number;
}

const employee: Employee = {
  name: "Bob",
  age: 25,
  employeeId: 1234
};

Explanation:

The Employee interface extends Person, adding an employeeId property.
This allows for the creation of more specific object types while reusing existing structures.

Exercises

Exercise 1: Define an Interface

Task: Create an interface Book with properties title, author, and publishedYear. Then, create an object myBook that adheres to this interface.

Solution:

interface Book {
  title: string;
  author: string;
  publishedYear: number;
}

const myBook: Book = {
  title: "The TypeScript Handbook",
  author: "John Doe",
  publishedYear: 2021
};

Exercise 2: Create a Type Alias

Task: Define a type alias Status that can be either "active", "inactive", or "pending". Use this type to declare a variable currentStatus.

Solution:

type Status = "active" | "inactive" | "pending";

let currentStatus: Status;
currentStatus = "active"; // valid
currentStatus = "inactive"; // valid

Feedback: Ensure that the variable currentStatus only accepts the specified string literals. Any other value should result in a TypeScript error.

Conclusion

In this section, you learned how to use TypeScript interfaces and types to define the structure of your data. These tools are essential for writing clear and maintainable code, especially in complex test scenarios. In the next section, we will delve into debugging Playwright tests, building on the strong foundation of TypeScript knowledge you've gained.

Using TypeScript Interfaces and Types

Key Concepts

What are Interfaces and Types?

Differences Between Interfaces and Types

Practical Examples

Defining an Interface

Using Type Aliases

Extending Interfaces

Exercises

Exercise 1: Define an Interface

Exercise 2: Create a Type Alias

Conclusion

Playwright with TypeScript: From Beginner to Advanced

Module 1: Introduction to Playwright and TypeScript

Module 2: Getting Started with Playwright

Module 3: Playwright and TypeScript Basics

Module 4: Advanced Playwright Features

Module 5: Test Automation Strategies

Module 6: Advanced TypeScript Techniques

Module 7: Real-World Playwright Applications

Module 8: Course Conclusion and Next Steps