free ebook and tutorial - Evolving JavaScript

JavaScript 2.0 is the next major revision of the JavaScript language. Also known as ECMAScript Edition 4, it is being standardized by the ECMA organization. This paper summarizes the needs that drove the revision in the language and then describes some of the major new features of the language to meet those needs — support for API evolution, classes, packages, object protection, dynamic types, and scoping. JavaScript is a very widely used language, and evolving it presented many unique challenges as well as some opportunities. The emphasis is on the rationale, insights, and constraints that led to the features rather than trying to describe the complete language.


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