JavaScript and Open Data

Introduction to Part 1

This part deals with the fundamentals of JavaScript, whatever the environment in which it is hosted. Most of the time, JavaScript is associated with a browser, but it is a language by itself. We use the term “Core JavaScript” or “ECMAScript” to mean what is “pure JavaScipt”, in contrast with what is added by the environment into which JavaScript is embedded.

There is no need to be a JavaScript expert, good applications can be quickly programmed, provided that you adopt some “good practices”. Coding without good practice (aka. “anti-pattern”) may seem correct while being silently error prone, with errors difficult to spot. That is why you will find “Recommendations” paragraphs throughout the chapters, suggesting ways to encode “patterns”. ES5 and ES6 standards facilitate this type of coding.

Part 1 can be used as a manual: going directly to the section that concerns one immediate problem, or instead studying a chapter more in depth, for instance with the sensitive issues of the language (e.g. prototypes, closures). Here is a quick tour of the features of this amazing language:

– Variables: declaration, definition, types (ban every “var”):

Here, we insist on the subtle distinction between the status of “declared” and “defined” variables, which deserves a particular attention. In this chapter, the creation of the tree structure of “variable scopes”, the implicit “hoisting” and the (dangerous) implicit declaration of global variables are presented. The ES6 ...