I don‘t personally work with node for the backend but typescript/javascript in the browser. And I think what is meant is something like LINQ in C# (all kinds of functions you can apply on enumerables/arrays), some basic DateTime library (how to add two dates in JS? How to get the diff of two dates in days or hours in JS? Both are 1 liners in C#) and maybe some more stuff for string mutation and so on.
https://github.com/tc39/proposal-temporal
JS standard libraries are forever. It pays to take a bit more time and get it right.
Who maintains day.js? It‘s (i did not look, i guess) not the same people that develop the JavaScript standard library. At some point, day.js is abandoned or breaks something and nobody is going to fix it because it is abandoned, or even worse, soneone creates a fork and fixes it there and now we have 2 day.js.
If it is in the standard library, you have a guarantee that it works today, works tomorrow and with a quite high certainty still works the day after. There are not that many languages that successfully break backwards compatibility often.
And don‘t get me started with the legal aspect. There are many projects where one cannot simply pull another dependency just to calculate a date diff.
Regarding Moment, on their site and they plaster exactly why you should not use moment and explain exactly why other libs (Day.js included) are better. Node is designed to be modular, Java isn't.
A language should provide a set of functionality that makes the developers life easier and consists of a set that he can achieve basic (daily) things without the need of 3rd-party dependencies. And if that usually starts with „npm -i“ I‘m going to question that...
- There's a tendency in the ecosystem to abandon projects rather soon: This can certainly happen, but it's important to choose libraries and frameworks carefully. My node servers (Express.js) are extremely light weight, so I rarely have this problem.
- Lack of multi threading: I think you are wrong on this point but I don't know your expectations since I'm not a Java developer. I have written some multi threaded code and saw massive perf improvements. You can't expect a scripted language to perform like Java, but quality of code is also very important. I wrote a generator that replaced a Java utility that was 10x faster. I rarely have to worry about this because it's easier to write async code that's extremely fast.
- Lack of typing: this seems more like a criticism of javascript.
I get that this isn't the platformm for you, but I think you might be wanting it to be too much like what you are familiar with.