If there is a Node-specific library, i.e. a lib that uses the require global, the fs module, etc., then you can, in many cases, use the Node compat module from the Deno std lib and just drop it into your project.
That being said, there's of course a Deno-specific ecosystem of libs, too, i.e. libs that use the Deno global. So you might find a suitable replacement if your favorite Node lib is not compatible for some reason.
After working with node.js for more than eight years I decided to give deno a try (https://github.com/bermi/genetic) and I’ve been gratefully surprised by the development experience.
I’m just missing a simple way to include deno code on my existing node.js and browser projects.
Edit: Well, someone touched a nerve! Doubt me, downvoters? You need but google to find a wealth of information to support the statement. https://www.imaginarycloud.com/blog/deno-vs-node/ is the first result, and there are a litany of other articles explaining the same.
That's a fairly… direct way of putting it :-)
Anyway:
1. What are the key differences in terms of usage and use cases?
2. Why isn't Deno a 'wholesale' replacement for Node?
3. In which respect are the vastly differently inner workings relevant in regards to usage of both products?
Here's what I discovered as what I presume andrew_'s reasoning for why its not a node replacement (from the article)
"Node has been under development for over a decade, which makes it more stable and battle-tested, making it the de facto standard for server-side JavaScript. Deno has only been under development for just two years and continues to be improved. Among other things, Deno is an excellent replacement for utility scripts that are usually written with bash or python."
So to answer the original question, "Does Deno work for frontend?", the premise of the question is inaccurate because Deno is an environment where you can run TypeScript code. It doesn't make sense to "run Deno in the frontend" (though maybe you could come up with some wasm monstrosity enabling an approximation of it). The better question would be, "can I share (as in re-use) TypeScript code in Deno and the Frontend?" to which the answer would be mostly yes -- but you'll still likely end up needing bundlers like webpack to help with it.
I'd say it has lower friction in general since Deno is using Web APIs, e.g. the fetch API is built-in (see https://deno.land/manual@v1.9.1/runtime/web_platform_apis).
One of good things about Deno is that it has golang-like opinionated/standardized workflow.