Cognitive stress has always been a challenge when dealing with new languages, features and APIs. Oftentimes, we find ourselves experimenting with new features, rather than only reading their documentation. Either with a debugger, a REPL environment, or a thousand console.logs, we explore what these tools do. But what if there was something that will further cut the time between writing code and seeing the result? JS Eval is a tool that achieves exactly this by displaying the evaluation results of your program directly where they come from. Join me as we dive into its plethora of features and how they can help you understand the new tools you encounter!

The "Language Server Protocol" (LSP) is a "don't call us, we'll call you" plugin mechanism for arbitrary programming language support for IDEs such as VScode. The protocol clearly separates the "what" (syntax, static semantics, dynamic semantics, refactorings) from the "how" (scheduling asynchronous jobs, interprocess communication, caching, (de)serialization, visualization, UI interactions, editors) in IDE construction.

In this talk, we demonstrate how to construct an LSP server for your own language, be it a programming language or a domain-specific language. We use the Rascal meta-programming language, which allows us to express programming language syntax and semanticson the abstraction level of the language, without even thinking about lower-level implementation details. Such a language prototype canbe wired directly into a "parametric" LSP (one that works for all languages made in Rascal). In other words, only the "what" is left,and the "how" has been completely automated.

Rascal, LSP, and VScode are a potent combination for designing and deploying your own languages, but when we add Gitpod to the mix,the languages really come alive immediately. We demonstrate a Logo-like programming language designed for high school students, one they can extend and adapt themselves, to run directly in the browser with some nice visual effects.

WebStorm IDE is researching developer experience flow state. We found that developers feel it is not productive alt-tabbing between IDE/ AI Agents, Figma and browsers trying to spot if everything matches. It’s a manual process that doesn’t scale when we are getting faster with AI. It's too late if these visual bugs hit a PR review, you've already lost the context needed to fix them without taxing your head space.

Is it possible or even desired to pull this validation directly into the development loop?
We'd like to show you our prototype on how we would like to combine the Figma Plugin APIs, WebStorm and Vitest Browser Mode to automate these checks while you code.

TC39 is the standards committee that designs the JavaScript language (sometimes called ECMAScript). The panel will feature a range of committee members and they will answer to questions about the past, present and future of JavaScript!