Reviewers have raved about previous editions of Wrox’s Professional JavaScript for Web Developers earning the most recent edition ninety-nine reviews averaging 4.4 stars out of 5 on a popular online bookstore. Real developers reviewed it with comments as technical as  "After going through this book in its entirety (twice for good measure :) ...), I can truly say that I am a more efficient, cleaner, and certainly more sophisticated JavaScript developer. I highly recommend this book for anyone looking to learn the latest ECMA 5.x has to offer (I previously coded to ECMA-262 version 3 based JavaScript only), " and as to-the-point as "If you want to become an expert in JavaScript, this is the book for you."The 4th edition continues the previous 3 edition tradition of jumping straight into deep technical details without kid gloves but updates the book for ECMAScript 6, new frameworks and libraries that are increasingly essential to web developers, and introduces readers to writing tests for JavaScript which is an often neglected part of a web developer’s training.The book is a major overhaul of the previous edition due largely to ES6 being a total re-imagination and departure from ES 5.1. Coupled with changes in the way people program in the time since the last edition and the growth of mobile web traffic, Professional JavaScript for Web Developers 4th Edition will introduce previous readers and other JavaScript professionals to a whole new style of JavaScript.New and heavily revised topics for this edition include: ES6 Classes Emerging APIs Web Animation Testing including mocks, unit tests, functional tests, and testing tools Planning for the ES "Harmony" future releases Build Systems Typescript

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