Skip to Content
Learning TypeScript 2.x - Second Edition
book

Learning TypeScript 2.x - Second Edition

by Remo H. Jansen
April 2018
Beginner content levelBeginner
536 pages
13h 21m
English
Packt Publishing
Content preview from Learning TypeScript 2.x - Second Edition

Dependency injection versus dependency inversion

Many articles use the terms dependency injection and dependency inversion as if their meanings were identical, but they are two very different concepts.

The following example declares a class named Ninja and a class named Katana. The Ninja class has a dependency on the class Katana:

class Katana { 
    public tryHit(fromDistance: number) { 
        return fromDistance <= 2; 
    } 
} 
 
class Ninja { 
    public constructor( 
        private _katana: Katana 
    ) {} 
    public fight(fromDistance: number) { 
        return this._katana.tryHit(fromDistance); 
    } 
} 

After declaring the preceding classes, we can inject an instance of Katana into the Ninja class:

const ninja = new Ninja(new Katana()); ninja.fight(2); // true ninja.fight(5); // false ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

Mastering TypeScript - Fourth Edition

Mastering TypeScript - Fourth Edition

Nathan Rozentals
Learning TypeScript

Learning TypeScript

Josh Goldberg
TypeScript for Beginners

TypeScript for Beginners

Bharath Thippireddy

Publisher Resources

ISBN: 9781788391474Supplemental Content