TypeScript -Interfaces

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Typescript: Zero to Hero
An Introduction to Interfaces


This module introduces you to Interfaces in TypeScript.

Learning Objectives

The objectives of this module are to provide you with an understanding of:

  • How to use Function Types
  • How to use Optionals
  • How to use Excess Property Checks
  • How to use Indexable Types
  • How Interfaces work with Classes
  • How to create Extendable Interfaces

Intended Audience

This learning path is aimed at all who wish to learn how to use TypeScript


It is essential you understand the face of contemporary web development to attend this course. You should have a good working knowledge of Javascript. Please note: Before attending this class delegates must have a Microsoft account (signing up one is free).


We welcome all feedback and suggestions - please contact us at qa.elearningadmin@qa.com to let us know what you think.


Interfaces are an important aspect of object-oriented programming. In this module, we'll investigate how to create and use interfacing TypeScript, apply inheritance to them, and understand how excess property checks are done. JavaScript follows single inheritance, so like in other languages, interfaces can be used to add extra rules to classes, but they can also be used to define the shape of objects for use in functions. An interface is like a contract. When we sign up to it, or make a class implement it, we must follow the rules of interface or face error messages. They're a bit like abstract classes, with only abstract methods and properties. No concrete implementation or data is held within an interface. Interfaces are duck typed. The compiler simply checks that we have at least the required members. The argument to the function need not be an instance or match the interface exactly. It just needs to satisfy its requirements, and it's important to remember that interfaces are just more syntactic sugar.


About the Author
Learning paths6

An outstanding trainer in software development with more than 15 years experience as a Corporate and Apprentice Trainer, ICT Teacher and Head of Department, with a passion for technology and its uses. Continuing to develop existing and new skills and courses, primarily in web design using PHP, JavaScript, HTML, CSS and SQL but also OOP (Java), programming foundations (Using Python), DevOps (Git, CI/CD, etc) and Agile/Scrum. Practically minded, a quick learner and a problem solver with an attention to detail to ensure high quality outcomes.

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