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.
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.
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.