What makes an empty object qualify as an Iterable or Array-like object?

Given Array.from takes an iterable or array-like object as it's first argument, why does it not throw an error when passed an empty object, like this:

let emptyObject = Array.from( {} )

At iterable is defined as an object that implements the iterable protocol or the iterator protocol. An empty object seemingly does neither:

let emptyObject = {}

console.log(emptyObject[Symbol.iterator])
console.log(emptyObject['next'])
console.log(Array.from(emptyObject))

An Array-like object has a length property and can be indexed (ref). An empty object does not have a length property.

let emptyObject = {}

console.log(emptyObject['length'])
console.log(Array.from(emptyObject))

How does an empty object qualify?

Array.from() works with array-like objects. More specifically it only really needs the length property:

console.log( Array.from({length: 5}) ); //array with 5 slots

This is defined in starting at step 7. of the Array.from algorithm

23.1.2.1 Array.from ( items [ , mapfn [ , thisArg ] ] )

[...]

7. Let arrayLike be ! ToObject(items).
8. Let len be ? LengthOfArrayLike(arrayLike).

[...]

LengthOfArrayLike is only this step:

7.3.18 LengthOfArrayLike ( obj )

[...]

Return ℝ(? ToLength(? Get(obj, "length"))).

Which means to retrieve the value of the length property of an object and defer to ToLength to convert it to a number. ToLength is defined as the following:

7.1.20 ToLength ( argument )

[...]

1. Let len be ? ToIntegerOrInfinity(argument).
2. If len ≤ 0, return +0_𝔽.
3. Return 𝔽(min(len, 2⁵³ - 1)). Therefore a missing length means argument is undefined which at step 1. would be converted to zero.