Just JavaScript is an attempt to understand JavaScript for what it really is - a very different language that should not be compared to Java or dismissed as simply a scripting language. It looks at the ideas that originally motivated the JavaScript approach and also at the additions over time that have produced modern JavaScript/ECMAScript. It isn't a complete introduction to JavaScript and isn't for the complete beginner to programming. It has been written for those who are familiar with the basic constructs used in any programming language and have already encountered JavaScript. After reading it, you will have an understanding how and why JavaScript is unique and the way in which you can exploit its strengths. After a brief overview of its history, we come to the key idea in JavaScript: it is object-based. Everything in JavaScript is an object and three chapters are used to introduce objects before we meet the Function Object. The many different ways of creating a JavaScript function tends to hide the fact that they are indeed all objects with properties and a lifetime that is different from local variables. This is the reason closure is natural. Having explored JavaScript's unique approach to parameters we are ready to consider how functions become methods. After this factory functions and constructors seem obvious as does the prototype chain. The final three chapters tackle the issues that are usually seen as problems for JavaScript and which are now reconciled within the idiomatic approach.