Chapter 2. Primitive Data Types, Arrays, Loops, and Conditions

Before diving into the object-oriented features of JavaScript, let's first take a look at some of the basics. This chapter walks you through the following:

  • The primitive data types in JavaScript, such as strings and numbers
  • Arrays
  • Common operators, such as +, -, delete, and typeof
  • Flow control statements, such as loops and if-else conditions


Variables are used to store data; they are placeholders for concrete values. When writing programs, it's convenient to use variables instead of the actual data, as it's much easier to write pi instead of 3.141592653589793, especially when it happens several times inside your program. The data stored in a variable can be changed after it was ...

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