Null and Undefined

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Typescript: Zero to Hero
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Overview
DifficultyBeginner
Duration19m
Students88
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Description

This module will introduce you to Simple Types in TypeScript. You’ll learn about Arrays, Tuples, and Type Assertion, too.

Learning Objectives

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

  • What Simple Types are
  • How to use Arrays
  • How to use Tuples
  • How to use Type Assertion

Intended Audience

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

Prerequisites

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).

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Transcript

The null and undefined primitive Javascript types are not very useful by themselves. I can assign null and undefined to other types such as number, string, any, and even void. If we compile this file, you can see that it compiles without any errors. However, TypeScript's compiler has a strict null checks flag, and this changes the behavior here. Observe what happens when we use the strict null checks flag. When added to the compiler you can see that we get some errors. We're not allowed to assign makeMeNumeric to null or undefined, but you are allowed to make the any type null or undefined. You can also see that the void type can only be assigned to undefined. It is recommended that this always be turned on, as it helps avoid many common errors. If you want to pass in a type with null or undefined as well, a union type could be used. Alternatively, set numerics to zero, strings to an empty string, objects to an empty object and so on, rather than null or undefined unless a specific need exists.

Lectures

Simple Types: An Introduction - Arrays - Tuples - Any and Unknown - Function Arguments and Return Types - Enums - Type Assertion 

About the Author
Students3050
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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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