As someone who has built a number of data products w/ React, I decided to give Svelte a try a few months ago. At this point I am using it on some internal projects to great success & ease and probably wouldn't go back to React for newer projects unless there was a compelling reason to (eg collaboration w/ other React devs). As a disclaimer, I admire the React community + devs and think React has made a lot of hard things much, much easier.<p>A few unvarnished takeaways from a data science / viz point of view that I was thinking of writing up, but will use HN as a sketchpad:<p>1. I don't really miss the React 3rd party ecosystem as much as I thought I would. Since most of what I do is data viz / data presentations, I really just need a few d3 helper functions, and most other things I can build myself w/ svelte's affordances. The biggest downside, however, is that there aren't any good accessible UX component libraries for Svelte, so I have built my own. This all said, I'm productively code-homesteading and I love it. Animating component lifecycles, component style scoping, and state management are 1st-class citizens, so these pieces are pretty high-quality, usable, and thoughtfully built.<p>2. my "time to first meaningful render" metric was at an all-time low with Svelte. Getting started on a new idea or project is far, far easier than w/ any React project I've ever done. Substantially less boilerplate means I can get much, much more done in the same amount of time. I feel this every time I jump back into the React projects I work on & maintain.<p>3. as my apps have grown in complexity, I've found that Svelte really holds up beautifully. The style/layout/behavior colocation strategy keeps the cognitive overhead of working on all the parts of multiple components to a minimum. The performance gains of Svelte, even with complex components and interactions, feels magical. Bundle sizes are bizarrely small.<p>4. as someone who feels CSS will absolutely outlive all of these frameworks, I think the design of Svelte really feels like the best of both worlds. And that's how it should be – css + markup should be first-class citizens.<p>5. the testing story isn't fully there yet, so I would say to that end, proceed with caution. I typically try to compartmentalize JS logic from presentation as much as possible, but perhaps you don't.<p>6. the reactivity parts shine everywhere and are fairly easy to reason about in all cases, but they REALLY shine when you're building complex visualizations.<p>7. this is an important one to me – building something in Svelte really tickles the same part of the pleasure centers of the brain that JQuery did for a previous generation (and d3 did for early data scientists). You just SEE the thing work, effortlessly, at a low cognitive cost, and everything fits together so nicely. I often start svelte-powered experiments and end with a great, reusable component. I think there is a large group of engineers who remember the JQuery days and sat out the React era because it just seemed like way too much to do simple things. I think Svelte is especially for them.<p>In sum, really highly recommended to at least try it. I wanted to find evidence to discount Svelte, but haven't found any at this point, despite my best efforts. There is probably a certain class of dev that should be trying it – one without a ton of organizational constraints, probably. But if you do data science and want to level up your data presentation skills, you should be using Svelte imo.