JavaScript Cookbook, 2nd Edition

Chapter 1. The JavaScript Not-So-Simple Building Blocks

Most JavaScript functionality comes to us via a very basic set of objects and data types. The functionality associated with strings, numbers, and booleans is provided via the String, Number, and Boolean data types. Other fundamental functionality, including regular expressions, dates, and necessary mathematical operations, are provided via the built-in RegExp, Date, and Math objects, respectively.

The fundamental building blocks of JavaScript have changed over time, but their core functionality remains the same. In this chapter, I’m focusing less on the syntax associated with the objects, and more on understanding their place in JavaScript.

Note

A good, introductory overview of the JavaScript standard built-in objects can be found in the Mozilla Developer Network JavaScript Reference.

Differentiating Between a JavaScript Object, Primitive, and Literal

Problem

People toss around terms like object, primitive, and literal. What is the difference between the three, and how can you tell which is which?

Solution

A JavaScript literal represents a value of a specific type, such as a quoted string (String), floating-point number (Number), or boolean (Boolean):

"this is a string"
1.45
true

A JavaScript primitive is an instance of a particular data type, and there are five such in the language: String, Number, Boolean, null, and undefined. The following are examples of JavaScript primitives:

"this is a string"
null

Of the primitive data types, three ...