Rediscovering JavaScript

Class Expressions

Class expressions are useful to create dynamic classes at runtime based on, for example, properties you read from a file, database, or user-provided input. Imagine creating a class factory function that will create and return a class—that’s a good place to use a class expression.

JavaScript supports both a class statement—which you use to define a class—and a class expression. The two key differences between a class expression and a class statement are

• The class name is optional for class expressions but required for class statements.

• The class expression should be treated as an expression—that is, it should be returned, passed to another function, or be stored in a variable.

Class statements are more common than class expressions, ...