Empty arrays seem to equal true and false at the same time

Answer 1

In if (arr), it is always evaluated (ToBoolean) to true if arr is an object because all objects in JavaScript are truthy. (null is not an object!)

[] == false is evaluated in iterative approach. At first, if one side of == is primitive and the other is object, it converts object to primitive at first, then converts both sides to Number if both sides are not string (string comparison is used if both sides are strings). So the comparison is iterated like, [] == false -> '' == false -> 0 == 0 -> true.