Javascript's async feels a bit more natural than Python's.
In Python, you've also got to run the event loop and pass the async function to it. This makes playing with async code in the interpreter more difficult. Also don't forget that async is also turtles all the way up (same as in JS). It'll infect any synchronous code that touches it.
I've written a Tornado app which makes heavy use of asyncio, and while it's pretty efficient, I would reconsider writing it the same way if I had to go back in time.
It's not bad anymore with async/await and promises/futures, but that featureset is still bleeding-edge in most languages. Older-style async code was much more annoying.
In your example the async code doesn't really help anything though - the next statement has to wait for the response from the previous one before continuing.
In your example you'd probably want to be using Promise.all to run two IO operations simultaneously.
The next statement has to wait, but the runtime can yield to another waiting async task so you aren't blocking the total throughput of your program (assuming it's async-all-the-way-down).
The benefits are generally larger-scale than a single method.
Thats hardly applicable async code. You're awaiting the actual async operations, which originally have to be distributed asynchronously from the main thread for these async operations to execute, and at that point its the same speed as just doing sync operations inside of an async operation.
Actual asychronocity, usually with event based systems, gets very ugly, very fast, because you end up having to make callback chains and queueing up your async work. There can be a good benefit to doing it, but its going to be a lot less readable than most sync code, and sometimes not any faster, in the case of Node.JS and its community forcing the usage of async function in places where they don't need to be used.
That code probably represents one function in a event loop webserver processing more than one request at a time. Non blocking behavior is important for work involving UIs.
Depends on you dev environment. Almost all of the browser dev tools should catch up eventually. The fun of an ecosystem with multiple competing implementations.
In Python, you've also got to run the event loop and pass the async function to it. This makes playing with async code in the interpreter more difficult. Also don't forget that async is also turtles all the way up (same as in JS). It'll infect any synchronous code that touches it.
I've written a Tornado app which makes heavy use of asyncio, and while it's pretty efficient, I would reconsider writing it the same way if I had to go back in time.