How is a member function defined within a class in JavaScript?

A member function, commonly referred to as a method in the context of a class in JavaScript, is defined using the shorthand syntax methodName() { }. This allows you to define the behavior of the class instances in a clear and concise manner.

When using this syntax, you define the method directly within the class body without the need for the function keyword. This is part of the class declaration syntax introduced in ES6 (ECMAScript 2015), which streamlined class creation in JavaScript.

By using this method definition, any instance of the class will have access to this function, allowing for encapsulated behavior that operates on the data held within the class. This improves the readability and organization of the code because it clearly indicates that these functions are part of the class's functionality, rather than being standalone functions or variables.

The other choices suggest alternative means of defining functions or behaviors in JavaScript, but they do not encapsulate the modern approach of defining member functions in classes directly using the class syntax.