Observable.from should handle "array-like" objects like arguments

[mattpodwysocki]

In order to be compliant with RxJS v4, Rx.Observable.from is missing the following functionality which brings it on par with Array.from. The current isArray check is too literal and should only check if it has a .length property

// Generate a sequence of numbers
Array.from({length: 5}, (v, k) => k);    
// [0, 1, 2, 3, 4]

And so does RxJS v4:

// Generate a sequence of numbers
Rx.Observable.from({length: 5}, (v, k) => k).subscribe(x => console.log(x));    
// [0, 1, 2, 3, 4]

Filing this bug as I did not see it in the test suite as it is in RxJS v4

[benlesh]

That's a horrible way to make a series of numbers. haha. Wouldn't users be better off using range for this? Do we really want them using from like that?

The better reason is so we can handle "array-like" types like arguments... basically anything with this shape:

var arrayLike = {
  "length": "3",
  "0": "foo",
  "1": "bar",
  "2": "baz"
};

So you can do things like Observable.from(arguments)

A better catch is that I don't think we have that result selector implemented.

[benlesh]

To fix this issue:

1. To handle array-likes, in particular arguments
2. To provide an optional resultSelector

[mattpodwysocki]

@Blesh yes, that's not a great example, and no, range won't do it. Instead, focus on array like objects such as any NodeList object to turn into an Observable

[benlesh]

I think this is closable as of now. The only hanging issue is defined by the discussion here #1255

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.