Comment by codedokode | Hacker News Reader

Comment by codedokode | Hacker News Reader

I wish instead of this marketing article there were technical details, for example: what method of change tracking is used (proxies Vue-style or recomputing everything React-style).

Also I didn't understand the phrase about JS "overflowing stack" with 150 000 objects. I created a list of 150 000 objects with the following code:

    var list = [];
    for (var i = 0; i < 150000; i++) { list.push({ id: i, name: `Name ${i}`, weight: i * 100 });  }

According to profiler, this array (with objects) uses 14 Mb, where 2 Mb is array and the rest are objects and strings. Running list.find() without any indexes also doesn't overflow the stack. With indexes it would probably be lightning fast and won't need any WASM and complications.

JS is not that slow. And if you do numeric computations (i.e. multiplication of numbers in large arrays) the code gets compiled and runs pretty fast.

The author uses something like `list.push(...objects)` in his demo code, and I believe this is the culprit. Passing many (~100,000) arguments to a method at once using the spread operator is known to cause a stack overflow, because, in JavaScript, each argument is placed on the call stack.

Spreading arrays and objects is such a common performance hit. It works fine for small instances but falls over in large instances.

Here's the JS CRM engine https://github.com/nuejs/nue/blob/master/packages/examples/s...

I see a number of issues, but don't have time to look into them.

1. Spreading when you probably don't need a copy: sortEntries. Sorting is probably where the overflow happens. Just sort in place or use Array.from or slice.

2. Excessive use of array functions. In my experience, a C style for loop performs better when you need performance. Create an empty array before, perform your business logic inside the block, and push to the array.

3. I don't know how filter is called, but it potentially loops through all of the events three times in the worst case.

4. paginate manually creates a JSON string from the returned entries. I don't know why, it seems inefficient.

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