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JavaScript The Definitive Guide
JavaScript is the programming language of the Web. The overwhelming majority of modern websites use JavaScript, and all modern web browsers—on desktops, game consoles ,tablets, and smart phones—include JavaScript interpreters, making JavaScript the most ubiquitous programming language in history. JavaScript is part of the triad of technologies that all Web developers must learn: HTML to specify the content of web pages ,CSS to specify the presentation of web pages ,and JavaScript to specify the behavior of web pages.
If you are already familiar with other programming languages,it may help you to know that JavaScript is a high-level,dynamic,untyped interpreted programming language that is well-suited to object-oriented and functional programming styles. JavaScript derives its syntax from Java,its first-class functions from Scheme,and its prototype-based inheritance from  you do not need to know any of those languages,or be familiar with those terms,to use this book and learn JavaScript.
The name ‘JavaScript’is actually somewhat  for a superficial syntactic resemblance, JavaScript pletely different from the Java programming  JavaScript has long since outgrown its scripting-language roots to e a robust and efficient general-purpose  latest version of the language(see the sidebar)defines new features for serious large-scale software development.
Lexical Structure
The lexical structure of a programming language is the set of elementary rules that specifies how you write program in that is the lowest-level syntax of a language;it specifies such things as what variable names look like,the delimiter characters ments,and how one program statement is separated from the short chapter documents the lexical structure of JavaScript.
Types,Values,and Variables
Computer programs work by manipulating values, such as the number or the text “Hello World.”The kinds