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Mastering JavaScript Design Patterns - Second Edition by Simon Timms

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Objects in JavaScript

JavaScript is an object oriented language but most people don't make use of the object oriented features of it except in passing. JavaScript uses a mixed object model in that it has some primitives as well as objects. JavaScript has five primitive types:

  • undefined
  • null
  • boolean
  • string
  • number

Of these five, only two are what we would expect to be an object anyway. The other three, boolean, string, and number all have wrapped versions, which are objects: Boolean, String, and Number. They are distinguished by starting with uppercase. This is the same sort of model used by Java, a hybrid of objects and primitives.

JavaScript will also box and unbox the primitives as needed.

In this code you can see the boxed and unboxed versions of JavaScript ...

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