Introduction to JavaScript Object Notation

Chapter 1. What Is JSON?

Before we look at JSON from a low-level point of view, let’s take a look at JSON from about 6,000 feet. From the mountain summit, we can see JSON flitting about in the world, carrying data in its lightweight format. If we look through our binoculars at JSON, we will see data among many curly bracket characters ({}). However, if we step back, and watch how it’s being used, we will ultimately see that it is a data interchange format.

JSON Is a Data Interchange Format

A data interchange format is a text format used to exchange data between platforms. Another data interchange format you may already have heard of is XML. The world needs data interchange formats, like XML and JSON, to exchange data between very different systems.

Imagine for a moment a world comprised of hundreds of tiny, isolated islands among a vast ocean. Each island has its own unique language and customs. The islands all have seafaring merchants that travel long distances between the islands. Outside trade is an integral part of all the island economies and contributes to a high standard of living for the islanders. If it weren’t for the highly trained carrier seagulls, this would not be possible.

The carrier seagulls move from island to island, carrying a paper report of data on which goods are in the highest demand. This way, merchants find out where they should move to next, and which goods they should acquire before embarking on their long voyages across the oceans. This important data allows all the islands to prosper without the threat of shortages.

Keep in mind, each island speaks a different language. If the data were passed around in several languages, each island would need to invest in researchers to learn all the world’s languages and employ a team of translators. This would be expensive and time consuming. This is an intelligent world, however, so the islands all agreed on a single language with a standard format for communicating their trade data. Each island employs just a single translator that understands the one data format of the trade reports brought by the carrier seagulls.

The real world of technology is much like the imagined island world example. There is a vast ocean, full of islands that have different languages, customs, and architecture. The ability for these unique systems to communicate is integral to many businesses and organizations. If each of these systems needed a translator for all the many ways other systems structure their data, then communications would consume an unreasonable amount of time and resources. Instead, the systems agree on a single format for data and employ a single translator.

JSON is a data interchange format that many systems have agreed on using for communicating data. You may hear it referred to as a “data exchange format,” or simply a “data format.”  In this book, I will refer to JSON as a data interchange format because the definition of “interchange” reminds us that the data format is intended for two or more entities exchanging it.

Many, but not all systems have agreed on JSON for communicating data. There are data interchange formats, such as Extensible Markup Language (XML), that were around before JSON was even thought about. The real world is not quite as simple as the island example. Many systems have and still use other formats, such as XML, or more tabular, delimited formats such as comma-separated values (CSV). The decision by each island in the real world for which data format to accept for communication often has to do with how the data format relates to the customs, language, and architecture of the island.

In the island world example, each of the hundreds of islands had its own language. The data in the paper report that the carrier seagulls carried was in an agreed upon format that was independent of language. This way, a single translator of the trade reports data could be employed by each island. The same is true of JSON, except the data is carried across networks in zeros and ones instead of by seagulls. The translator isn’t a human, it is a parser employed by the system consuming the data so it can be read within the system it is entering.

JSON Is Programming Language Independent

JSON stands for JavaScript Object Notation. The name of this data interchange format may mislead people into thinking they will need to learn JavaScript to understand and use JSON. There would be some value in learning JavaScript before learning JSON, as it was born out of a subset of JavaScript, but if you will not be using JavaScript anytime soon it would be unnecessary. You may remain dedicated to the language or languages of your own island, for the spirit of a data interchange format is to be independent of language.

JSON is based on JavaScript object literals. A detailed explanation into the “how” of this is better suited for our discussion on syntax (Chapter 2) and data types (Chapter 3). For this chapter, the “why” is important. If a data interchange format is meant to be language independent, then it may seem contradictory to have a data format that is not only derived from a single language, but advertises it in its name: JavaScript Object Notation. Why, then?

If we return to the island example, imagine for a moment what the meeting to select the data format would have been like. When the representatives from each of the hundreds of islands arrived at this meeting, and looked to create a single data format, the first thing they would want to find is common ground.

The languages of each island may have been unique, but there were things the islanders found they had in common. Most of the languages were spoken primarily with the human voice and included a written form of the language represented by characters of some sort. Additionally, facial expressions and hand movements were also present. There were a few troublesome islands where the people communicated by other means, such as hitting sticks together or winking, but the majority of the islands found common ground with their written and spoken forms of language.

In the real world, there are hundreds of programming languages. Some are more popular and commonly used than others, but the language landscape is diverse. When college students major in computer science in preparation for a career in programming, they do not study all the programming languages. Students usually begin with one language, and the language itself is not so important as learning the universally accepted programming concepts. Once students gain an understanding of these concepts, they can more easily learn other programming languages through their ability to recognize the common features and functionalities.

If we set aside the word “JavaScript” from the name “JavaScript Object Notation,” we would be left with “Object Notation.”  In fact, let’s forget JavaScript all together. We could then say we are using an object notation data interchange format. “Object” is a common programming concept, in particular to object-oriented programming (OOP). Most computer science students studying programming will learn the concept of objects.

Without diving into an explanation of objects, let’s settle our attention on the word “Notation.”  Notation implies a system of characters for representing data such as numbers or words. With or without an understanding of objects in programming, it is not a stretch to see the value of having a notation to describe something that is common across programming languages.

Returning again to the island example, the islanders themselves found a notation that represented a common tie among the majority of languages. Most of the islanders had a similar way of representing numbers with tallies, and it was agreed they could understand a series of symbols for representing real-world objects such as wheat or fabric. Even the island that communicated by winking found this format acceptable.

Despite the agreement among the vast majority of islands, there were still a few islands, such as the island that communicated by hitting sticks together, that did not find the format understandable. A good data interchange format covers the majority, but there are usually outliers. When we talk about this coverage, a term often thrown around is portability. Portability, or the compatibility in transferring information between platforms and systems, is the very goal of a data interchange format.

Circling back to notation, the notation of JSON may originate from JavaScript, but the notation itself is the important part. Not only is JSON language independent, it represents data in a way that speaks to common elements of many programming languages. With the way that data is represented, such as numbers and words, even the programming languages that aren’t object oriented can find this format acceptable.

Key Terms and Concepts

This chapter covered the following key terms:

JSON

JavaScript Object Notation.

Notation

A system of characters for representing data such as numbers or words.

Data interchange format

Text used to exchange data between platforms or systems.

Portability

Transferring information between platforms in a way that is compatible with both systems.

We also discussed these key concepts:

• JSON is a data interchange format.
• JSON is programming language independent (JavaScript is not required to use it).
• JSON is based on the object literal notation of JavaScript (emphasis on the word “notation”).
• JSON represents data in a way that is friendly to universal programming concepts.