A Final Word

In this column we presented Part I of our series about object-oriented programming with JavaScript. We focused on the inheritance principle and how it is emulated by the language. We showed you two different ways to implement inheritance, and delved into the prototyping method. We demonstrated how to check for a superclass/subclass relationship between objects. We explained how to list an object's properties, and how to verify that indeed a certain property exists. We rounded up this column by a comparison of JavaScript and Java as object-oriented languages.

In this column, you have learned:

• How to characterize an object-oriented programming language
• How to implement inheritance with functions
• How to implement inheritance with prototyping
• How to add properties and methods after the object is created
• How to probe inheritance in NS with __proto__
• How to check for prototyping
• How to classify and print objects
• How to query an object's properties
• How to compare JavaScript and Java