I use typescript almost daily. It's certainly better than Python or Ruby, I'll grant you that. But I don't think Python is a good language either.

Ultimately I want a langauge with value types like structs and arrays that you can use to do computations without allocating things on the heap.

In Go I can write a function that returns two numbers.

In Javascript I can only return two numbers by allocating an array on the heap with two items. These two items themselves are probably pointers to two number objects allocated separately. So that's 5 allocations to return two numbers. It's insane.

This means fundamentally it's impossible to create applications in javascript that are both sophisticated and high performance.

A great example to illustrate this is the tooling around Javascript itself.

There were all kinds of bundlers: webpack, rollup, parcel, etc. Rollup was considered the fastest and lightest. They were all programmed in Javascript itself. They were all slow. But no one really knew how bad it was because there was nothing really better.

Then esbuild comes along, and blows all of them completely out of the water, out performing them by 100 times. And it's written in Go. A language that supports structs and arrays as value types.

It’s not fundamentally impossible to build fast apps in JS. It’s just not possible to do if you don’t do the legwork of writing code that the compiler will optimize for you. It’s not easy, and it’s not natural in a lot of cases, but saying it is fundamentally impossible goes too far: people build high performance applications like games in JS.

For example, you are worried about value types but under the hood the JIT compiler will actually generate efficient representations that are passed by value if you do not mess things up for it. Modern JS compilers are extremely sophisticated.

For returning values without an allocation, you’d create such a “struct” and then use a memory pool. It would still be heap allocated I believe but not totally sure. People who know more than I do could probably tell you a better method to return multiple values from a function efficiently.

> people build high performance applications like games in JS

Yes, and in my experience this kind of applications (and the browser in general) are one of the only things these days that still push me to upgrade my hardware to have better CPUs and more RAM, as it's perfectly sufficient as is for pretty much everything else I do.

You can’t tell from the outside if you are running a well engineered JS app that would have been fast in another platform, or a non-optimized JS app. My point was that it’s not fundamentally impossible to write fast enough JS code for a game, even though you may come across many slow JS apps regularly. (Not surprising, given the wide distribution and low barrier to entry of the web.)

Yes, you can operate strictly on typed arrays and essentially implement something alike a virtual machine inside your JS code to make it handle memory efficiently, so you're right - it's not "fundamentally impossible", but are you still really writing JavaScript at that point? :P