The concept of program objects is important in both Javascript and Java.
Objects are self-contained independent sections of code that can be made to work together.
Programs written in languages that use these constructs should be designed in terms of how the objects relate to each other, not merely as long strings of sequential instructions. A difference in the two types of languages is the fact that the former lets you define new objects as you see fit, but the latter primarily lets you use a set of predefined objects. Javascript has a set of objects that it associates with the browser, its various windows, and many HTML tags. One consequence of this is that it is sometimes possible to change portions of a web page dynamically with Javascript, without having to invoke a server script or reload the entire page. The Navigator Object Javascript has a navigator object that the language associates with the browser itself.