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

Optional members

We can define optional class properties and methods by appending the ? character at the end of the name of a property or method. This behavior is like the behavior that we observed in Chapter 3, Working with Functions, when we learned how to use the ? character to declare optional arguments in a function.

The following code snippet defines a class named Vector with an optional property named z. When we define a Vector instance using numeric values for the properties x and y, the Vector has two dimensions. When we define a Vector instance using numeric values for the properties x, y, and z, the Vector has three dimensions:

class Vector { public constructor( public x: number, public y: number, public z?: number ) {} public ...
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