TypeScript Development

Subjects

• Introduction
• Getting started
• Types
• Variable declaration
• Functions
• Interfaces
• Classes
• Generics
• Structuring code
• JavaScript interop
• Compiler
• Advanced types
• Advanced use cases
• Async/await
• Mapped types
• Template literal types
• Decorators - if time permits
• JSX Support - if time permits

Introduction

In this chapter, you will learn the context in which to place TypeScript. Goals:

• Learn how TypeScript relates to JavaScript.
• Know what "type-safety" means and how it relates to TypeScript
• Learn to use TypeScript in a regular JavaScript file.

Getting started

In this chapter, you will learn how to create a plain TypeScript application. Goals:

• Learn the basics of a NodeJS project.
• Learn the basics of tsc (typescript compiler)
• Know how to run an application in nodejs
• Know how to debug a TypeScript application.
• Learn some basic compiler options.

Types

In this chapter, you will learn how to declare and use primitive types in a TypeScript file. Goals:

• Know the primitive types.
• Understand what any does and why not to use it.
• Learn to use --noImplicitAny
• Learn to use --strictNullCheck
• Know the difference between null and undefined.
• Learn what literal types are.

Variable declaration

In this chapter, you will learn the different ways to declare a variable in TypeScript. Goals:

• Know the difference between blocked scope and function scope.
• Learn to use const and let.

Functions

In this chapter, you will learn the different ways to define and use functions and some related ES features. Goals:

• Learn to use functions in TypeScript
• Learn to use some recent additions to JavaScript, like spread operator and destructuring.
• Understand what this points to inside a function.
• Know the difference between function expressions and arrow functions

Interfaces

This chapter will dive into the heart of the type system: define the shape of objects with interfaces. Goals:

• Learn what a 'shape' is and how to name one.
• Learn the different ways to modify properties.
• Know how to use index accessors.
• Learn what a method shape is.
• Learn to use overloading in interfaces.

Classes

In this chapter, you will learn all there is to know about classes in TypeScript. Goals:

• Learn to use classes.
• Know the difference between private, public, protected, and ES private.
• Learn how to use prototypal inheritance.
• Learn how to use properties and when (not) to use them.
• Know to associate types with classes and class instances.
• Learn to love --strictPropertyInitialization.
• Know how to use method overloading.
• Learn what this points to inside a class body.

Generics

This chapter dives into generic type argument. Goals:

• Learn what a generic type argument is and why they are usefull.
• Learn to use type constraints.
• Learn to prevent a death by a thousand overloads using spreading parameter types.

Structuring code

In this chapter, you will learn how to scale your TypeScript application across multiple files.

• Learn the two ways to structure code in TypeScript
• Learn what a "module" is.
• Know the different output modes for modules.
• Know how to consolidate multiple modules into one.
• Know how to avoid some pitfalls with ES modules.

JavaScript interop

In this chapter, you will learn how to use JavaScript code from TypeScript. Goals:

• Learn how to import and use JS code.
• Know what a declaration file is and how to use them.
• Understand how type-resolution works.

Compiler

This chapter showcases useful compiler options, and introduces you to project references. Goals:

• Know how to include and exclude TypeScript files.
• Know all the essential options and strictness options.
• Understand when to use project references.
• Learn to split a program into multiple projects with project references.

Advanced types

This chapter showcases advanced type concepts. Goal:

• Understand the concept of "type compatibility"
• Learn to combine types with unions and intersections.
• Learn to name types with an alias
• Know the concept of a "type query".
• Learn to love the unknown type.
• Learn to perform type assertions and type guards

Advanced use cases

In this chapter, you will combine some advanced concepts of the previous chapter into use cases.

• Learn to create and use a discriminated union.
• Learn what the never type is and why it s usefull
• Learn to create an exhaustive check

Async/await

In this chapter, you will learn the concept of "Promises" in JavaScript and what TypeScript adds to this. Goals:

• Know the concept of "delayed work."
• Learn to work with promises
• Understand what async and await do to your program.
• Learn to use promises in the wild.

Mapped types

In this chapter, you will learn to define for-loops and if-statements inside TypeScripts type system. Goals:

• Know what a "lookup type" is.
• Learn how to create a simple mapped type.
• Know the build-in mapped types.
• Know what a conditional type is.
• Learn where conditional types can be helpful.

Template literal types

We end with a grand finally: defining and using template literals inside the type system. Goals:

• Know what a template literal type is
• Understand how to create a 'stringly typed' yet type-safe API.
• Know some basic string manipulation in the type system.

Decorators - if time permits

JSX Support - if time permits