Why do you like it? Serious question.
This got a lot bigger than i thought, so strap in!
* The lack of "private" anything. This sounds like a bad idea, but I firmly believe it was a major reason for JS's success. The ability to "monkey patch" anything including built-in functions and other libraries means that everything is extendible. It isn't something i do very often (mucking around with internals of another module/system) but when i do it's really fun and generally solves a problem that otherwise would be unsolvable.
* The debugging. Oh the debugging! It's magnitudes better than anything i've ever used before. And i don't just mean in features (i know that other langs have feature X that JS doesn't have, or can do Y better). I can use multiple debuggers, inspect EVERYTHING, breakpoints, live inline code editing, remote-debugging (on pretty much every mobile device), world-class profiling tools with memory usage, cpu usage, JIT performance, optimizations/deoptimizations, etc... Hell Edge is even getting "time travel debugging" where i can step BACKWARDS in code, edit it in place, then play it forward again! Also, sourcemaps! I can compile python/coffeescript/typescript/javascript to javascript and then minify it and combine multiple files, but when i open the debugger i see my source files, with their full filenames, and the execution is synced statement-by-statement. And they work for CSS too! And I almost forgot about the best part. Since they can be separate files, i can include them in my production build with literally 0 overhead. So if there are any problems with the live build, i can open the debugger and have the full development-mode first-class debugging experience, on the live site, even on a user's PC if i need to. Hell i can even edit the code in-place to see if my fix works! This one is probably one of my favorite features of javascript and it's ecosystem.
* async programming. Yeah, i know other languages have it, but JS is the first time where i would consider it a "first class citizen" Everything is async, it's amazing, and it's to the point that if something isn't async, it's almost a bug. And this combined with the event system and the single-threaded-ness means writing performant code is more "straightforward" than i've experienced in other languages. Combine this with web-workers (or threads in the node ecosystem) and you get the best of both worlds.
* the mix of functional and OOP programming. Functional programming sucks for some things, OOP sucks for others. I feel like in practice JS lets me use the best of both. Yeah, it's not "pure" or "proper", yeah you can use the worst of both, but i love it. You can add the mix of immutable vs mutable in this as well. By having both, it lets me choose which i want to work with for the current problem, even switching in a single project.
* it's fast. JS is pretty fucking fast in the grand scheme of things. Yeah, it's not C, but with typed arrays and some profiling (which JS makes oh so easy!) it's possible to wipe the floor with Python, Ruby, PHP, and can even give Java and Go a run for their money. For such a dynamic language, that's impressive.
* the compilation options. From coffeescript/typescript/flow, to just compiling between js "dialects", and adding non-standard (or extremely new) features to the language is "easy". It took me a little while to get used to being that disconnected from the final output, but once i "let go" of that, i found i loved it. With babel plugins i can add extra tooling, or extra type-checking, or even completely non-standard stuff like JSX or automatic optimizations into the code that i output. Combined with some good tooling i can even change how the code executes based on the "build" i'm generating (for example, i have some babel plugins that optimize react elements to improve first-load speed, but i only run it on staging/production builds because it is pretty verbose (which gets removed when gzipped) and is difficult to debug)
* the tooling. auto-refresh, hot-module replacement, automated testing, integration testing, beautiful output in multiple formats, linting, minifying, compressing, optimizing and more task runners than you'll ever need. The fact that i can write code, save, and have that code hot-replace the code currently running in my page on my PC, tablet, phone, laptop, and VM all at the same time. There is nothing that even comes close to this. At all.
* and i guess finally, npm. The fact that there are 5+ different modules for everything i could ever want. The fact that i can choose to install a 3-line program, or write it myself, or install it first and write it myself later, or vice versa. The fact that i can choose a module optimized for speed, or one for size. The fact that i can get a pure-js bcrypt and a natively-compiled bcrypt with the exact same API and install the native and if that fails fallback to pure-js. The fact that NPM installs are so effortless that i have a project with about 100 direct dependencies (and most likely about 1000 when it's all said and done), and there isn't even a hint of a problem is wonderful (this is a bit of an edge case though, most of the packages installed here are "plugins" like babel plugins, postcss plugins, and i'm purposely avoiding bundled deps kind of for shits-n-giggles.) And no matter how many internet commenters keep telling me i'm wrong, i haven't had any issues with it.
This got a lot bigger than i had intended, but the point is that while JS might not do any one thing very well, it does many things pretty damn well. And the benefits far outweigh the downsides for me.
I'm going to bed for the night, so if you reply don't expect an instant reply, but despite the "standoffish" nature of a lot of this, I want to hear responses.
To add to the part about extensibility, many times I have jumped into a "node debug" session, in my own code or in 3rd party modules installed to node_modules. Many times I have added breakpoints or tweaked 3rd party code right in node_modules, or monkey-patched methods temporarily. This kind of thing is often nearly impossible, very time consuming, or just plain difficult to do in other languages.
Regarding a lack of private anything, it's possible to monkey-patch any Lisp package or class however one wants. And of course, one can get true privacy in JavaScript if one wants, by using closures — the same trick applies in Common Lisp.
Lisp debugging is great: one can set up all sorts of condition handlers and restarts, and invoke them from the debugger.
Lisp is a great blend of imperative, functional & object-oriented programming styles, enabling you to use the right tool for the problem at hand.
Lisp is incredibly fast, faster than C & C++ in a few cases and almost always Fast Enough™. It's dynamic, but inner loops can be made very static for performance. There's even a standard way to trade off safety and performance, if that's what's important in a particular case.
I don't know for certain, but I believe that Lisp was the language that invented hot-patching (well, I suppose one could always have done it from assembler …). It was even used to debug a problem on a NASA probe[0]: 'Debugging a program running on a $100M piece of hardware that is 100 million miles away is an interesting experience. Having a read-eval-print loop running on the spacecraft proved invaluable in finding and fixing the problem.' As with JavaScript, the Lisp debugger is part of the standard and is always available. This can be profoundly useful.
And Quicklisp is a nice, modern way to pull down numerous libraries.
Lisp does of course support async programming since function are first-class, although I'm not personally as much of a fan as you are. Generally, I think that callback hell should generally be avoided.
I'm not aware of a lot of compile-to-Lisp projects, but given that the language is great at treating its code as data, it's an excellent target.
It certainly doesn't have the huge ecosystem that JavaScript does, but that improves with every developer who starts a project.
I really, really wish more folks would take a look at it. The more I use it, the more I realise that a 22-year-old standard has well-thought-out solutions to problems that people still face in other language environments today.
The only thing i have to add is that while callback hell sucks, there have been some pretty recent (in the grand scheme of things) additions to the async programming field. Async/await is beautiful, and it has made me fall in love with async programming all over again.
> I can use multiple debuggers
Multiple browsers means there are multiple competing sets of debugging tools, each are good at some things and worse at others. For example, Firefox was among the first to be able to properly debug promises, while chrome still let it swallow unhandled errors.
After writing that, i think the reason i love working with JS is because of the choice. A lot of that choice isn't necessarily because of the language (you could easily have that debugging experience in other languages), but it's currently in javascript.
"The lack of 'private' anything" - Just hearing this caused immediate revulsion and I am sorry to say that. Where I come from, the best practice is to try to keep everything closed from modification but still open enough for extension: http://www.cs.utexas.edu/users/downing/papers/OCP.pdf
"The debugging" - The features you mentioned are all available in the Java ecosystem as well. It is a very mature ecosystem with great IDEs, debuggers, performance testers, etc. The step-back and edit feature of debugging has been around for awhile now. Heck, you can even write your own debugger fairly easily due to good support of other tools in the ecosystem.
"async programming" - Not sure what you mean by "first-class citizen", but asynchronous programming can also be done with Java as well. Callbacks and futures are used widely (at least where I work). But even better: Java is multi-threaded. What happens to the Node.js server if a thread is getting bogged down?
"the mix of functional and OOP" - I admit I have no experience with functional programming so I can't say anything about mixing the two paradigms together. But I have seen OOP with Javascript and frankly, it is confusing and unwieldy. I don't even think the concept of class as an object blueprint exists. How do you even create a class that inherits the properties of another Javascript class? It is one of the basic ideas of OOP but I don't think Javascript supports it. From my brief time with it, it really looks like you only have simple objects with properties and methods which can be set up off of a prototype but that's it.
"it's fast" - Not sure where you got this idea. Looking at various benchmarks on the internet, they show that Javascript is significantly slower (sometimes by an order of magnitude) compared to Java, Go, and C++. I did notice that it looks to be faster than Python and Ruby. https://www.techempower.com/benchmarks/#section=data-r12 https://benchmarksgame.alioth.debian.org/u64q/javascript.htm...
"the compilation options" - I'm assuming you're are talking about transpilers and yes, I've been noticing more transpilers that target Javascript. I honestly don't know why one would want to do that though. It just seems an unnecessary layer. Why not just directly write Javascript code? Is the Javascript syntax so bad that you want to code in pseudo-Ruby (Coffeescript)? :)
"the tooling" - Hot swapping, test frameworks, linting, optimizing, ...these are also available in the Java ecosystem and have been for quite some time now. Notice I didn't mention auto-refresh, minifying, and compressing since I am not sure what exactly those are and I don't think they apply to compiled languages.
"npm" - The available libraries in the Java ecosystem is vast and a great number of them have been developed and iterated upon by some of the best engineers and computer scientists in the past ~20 years. And the Java libraries do not seem to have the problems that npm is suffering at the moment :P
per the debugging, i might have to take another look at this. I hadn't realized that it was that nice!
per async, yeah java can do async programming, but in js you MUST do async programming. Because of the single-threaded nature, if you aren't async you are blocking which ruins the performance instantly. This means that every library, function, and module is built for async from the start. "What happens to the Node.js server if a thread is getting bogged down?", it runs slowly or in some cases not at all. Yeah, that sucks, but this constraint forced better and more widely available async code. Plus if you really need multiple threads you can have them (webworkers on the web, threads on node), but you need to control them absolutely. It's more work, but it's the same outcome. I'd prefer this to be different, but trying to bring multi-threaded execution to javascript is like trying to stop a tornado with your bare hands...
per functional/oop, JS's OOP is lacking (or was, recently with ES6 it's gotten MUCH better). Now you can inherit from another class, now you can use a class as an object blueprint. There's still work to be done here, but it's getting better. That being said, there are ways to solve those same problems, but they are functional. And even though we are getting inheritance, it's largely an anti-pattern (at least to me). Composition is almost always prefered. Going back to my monkey-patched library from above, i was able to modify the object at runtime to add more functions and to "redirect" others. In something like Java i'd need to wrap that class in another class and add what i want there. It's largely the same result when used alone, but when you combine that, with a polyfill that's fixing something in all objects, and with a plugin for that library (where the lib wasn't meant to have plugins in the first place), in Java land you quickly end up with a big mess, while in JS land you can keep hanging more and more crap on an object if you want at runtime. And because the language was "meant" to be used this way, everyone expects and guards against it.
per speed. It's not as fast as java/go 90% of the time, but there are times where it can be. Yeah, they are the minority, but i was more just trying to dispel the myth that JS is dog slow. It's impressively fast these days. My favorite set of benchmarks to show off is the asm.js suite from "arewefastyet"[1]. It's more for comparing JS engines against each other, but there is a "Native C++" compiled version of the same code and they are comparing their JS against that.
The compilation options. It seems like an unnecessary layer, but in practice it's not as bad as many make it out to be. You still need to know JS to do it, so you are doubling the amount of languages you need to know to work on the project, but it does allow for some cool stuff. Typescript (microsoft's strong-er typed javascript/C# hybrid compile-to-js language) actually pushed a bunch of features into the newest version of javascript. Coffeescript did as well. These compile-to-js langs are partly a symptom of a problem, and by their nature they let people "solve" the problem now and when it gets fixed they can migrate back to "pure" js if they want. Also, it's this "transpiling" that lets things like React's JSX to exist. Adding entirely new, unrelated to javascript itself, parts to the language. JSX allows you to embed HTML directly into JS and it's basically a wrapper around the "document.createElement" function (in reality it's MUCH more, but that's the gist of it). It's really strange if you haven't used it before, but it's extremely powerful. And it could be done in other languages (and it is, look at go's generate command), but it's already here in js, and i love it!
the tooling, java is probably the only other one in my "list of languages" that is on the same level as JS in terms of tooling. The problem i have with Java's tooling is they tend to be built into IDEs instead of standalone tools. So that means i'm married to my IDE if i want those features. In JS land for the most part they are standalone and can be used with many different editors. This is a pain-point at my work currently as we are switching from a Business basic stack that marries you to the IDE and everyone wants different things in their next editor. It's a small problem though in the grand scheme of things, but it's a bit of a pet-peeve of mine.
and npm. Maven is great, but it just doesn't have the same number of options that something like NPM has. I know this isn't the languages fault (the best package manager doesn't mean shit if there are no packages), but it's a pain point. Many people seem to think of having "too many options" as a problem, but I think i'm spoiled by it now. If i want a lib to handle authentication in my app, i have 5 or more major choices. They all have their upsides and downsides, they are all made for different use cases. In something like the java world i just haven't seen that amount of choice. The only other one that comes close is surprisingly go. I really think the number of packages stems from ease of publishing, and npm (and go) have that down pat. I also think that this comes down to the languages being more oriented towards different things.
I appreciate the comment, and i'm in no way trying to say that JS is the only one that has these things (not that it sounded like you were implying it), but when combined, it makes for a nice experience.
[1]https://arewefastyet.com/#machine=28&view=breakdown&suite=as...