Use JsVal instead of JsRef in more places (nr. 3)

[hoodmane]

This also fixes JsArray_pop which leaked memory and returned a singleton list with the element removed rather than the element itself.

• Add a CHANGELOG entry
• Add / update tests

[ryanking13]

Thanks! LGTM with a question.

This also fixes JsArray_pop which leaked memory and returned a singleton list with the element removed rather than the element itself.

Nice!

[ryanking13]

Were we treating an empty JS object as a falsy value before?
I got a different result when I tried this.

a = {}
pyodide.runPython(`
from js import a
print(bool(a))
`)

True

[hoodmane]

Empty object was always truthy, but the test was written incorrectly. If you do eval("{}"), {} is parsed as an empty block not as an object. Thus, it returns undefined which is Falsey. I adjusted the test so it calls run_js(f"({js})") which calls eval("({})") which returns empty object with is truthy.

I think empty object is most comparable to:

class A:
   pass
bool(A())

We could do something like:

function isTruthy(obj) {
  if (obj.constructor !== Object && obj.constructor !== null) {
    return true;
  }
  for (const prop in obj) {
    if (Object.hasOwn(obj, prop)) {
      return true;
    }
  }
  // object with default or null constructor and no ownProperties
  return false;
}

[hoodmane]

Anyways I am open to switching to this in the future.

[ryanking13]

I see. Thanks for the explanation!

[hoodmane]

I added a lot of methods in the same PR with JsArray_pop, so it stands to reason that I forgot to test one.