International audienceJavaScript is the de facto programming language for the Web. It is used to implement mail clients, office applications, or IDEs, that can weight hundreds of thousands of lines of code. The language itself is prototype based, but to master the complexity of their application, practitioners commonly rely on some informal class abstractions. This practice has never been the target of empirical investigations in JavaScript. Yet, understanding it would be key to adequately tune programming environments and structure libraries such as they are accessible to programmers. In this paper we report a large and in-depth study to understand how class emulation is employed in JavaScript applications. We propose a strategy to statically detect class-based abstractions in the source code of JavaScript systems. We used this strategy in a dataset of 50 popular JavaScript applications available from GitHub. We found systems structured around hundreds of classes, suggesting that JavaScript developers are standing on traditional class-based abstractions to tackle the growing complexity of their systems

To implement modern web applications, a new family of JavaScript frameworks has emerged, using the MVC pattern. Among these frameworks, the most popular one is ANGU-LARJS, which is supported by Google. In spite of its popularity, there is not a clear knowledge on how ANGULARJS design and features affect the development experience of Web applications. Therefore, this paper reports the results of a survey about ANGULARJS, including answers from 460 developers. Our contributions include the identification of the most appreciated features of ANGULARJS (e.g., custom interface components, dependency injection, and two-way data binding) and the most problematic aspects of the framework (e.g., performance and implementation of directives).

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AngularJS is a popular JavaScript MVC-based framework to construct single-page web applications. In this paper, we report the results of a survey with 95 professional developers about performance issues of AngularJS applications. We report common practices followed by developers to avoid performance problems (e.g., use of third-party or custom components), the general causes of performance problems in AngularJS applications (e.g., inadequate architecture decisions taken by AngularJS users), and the technical and specific causes of performance problems (e.g., unnecessary processing included in the digest cycle, which is the internal computation that automatically updates the view with changes detected in the model).