What techniques can be used to define a class in JavaScript, and what are their trade-offs?

Question

I prefer to use OOP in large scale projects like the one I'm working on right now. I need to create several classes in JavaScript but, if I'm not mistaken, there are at least a couple of ways to go about doing that. What would be the syntax and why would it be done in that way?

I would like to avoid using third-party libraries - at least at first.
Looking for other answers, I found the article Object-Oriented Programming with JavaScript, Part I: Inheritance - Doc JavaScript that discusses object-oriented programming in JavaScript. Is there a better way to do inheritance?

Answer 1

Here's the way to do it without using any external libraries:

// Define a class like this function Person(name, gender){     // Add object properties like this    this.name = name;    this.gender = gender; }  // Add methods like this.  All Person objects will be able to invoke this Person.prototype.speak = function(){     alert("Howdy, my name is" + this.name); };  // Instantiate new objects with 'new' var person = new Person("Bob", "M");  // Invoke methods like this person.speak(); // alerts "Howdy, my name is Bob" 

Now the real answer is a whole lot more complex than that. For instance, there is no such thing as classes in JavaScript. JavaScript uses a prototype-based inheritance scheme.

In addition, there are numerous popular JavaScript libraries that have their own style of approximating class-like functionality in JavaScript. You'll want to check out at least Prototype and jQuery.

Deciding which of these is the "best" is a great way to start a holy war on Stack Overflow. If you're embarking on a larger JavaScript-heavy project, it's definitely worth learning a popular library and doing it their way. I'm a Prototype guy, but Stack Overflow seems to lean towards jQuery.

As far as there being only "one way to do it", without any dependencies on external libraries, the way I wrote is pretty much it.