[javascript] Javascript extends class

What is the right/best way to extend a javascript class so Class B inherits everything from the class A (class B extends A)?

Douglas Crockford has some very good explanations of inheritance in JavaScript:

1. prototypal inheritance: the 'natural' way to do things in JavaScript
2. classical inheritance: closer to what you find in most OO languages, but kind of runs against the grain of JavaScript

   extend = function(destination, source) {   
          for (var property in source) {
            destination[property] = source[property];
          }
          return destination;
    };

Extending JavaScript

You could also add filters into the for loop.