Why does “undefined equals false” return false?

Question

When I compare undefined and null against Boolean false, the statement returns false:

undefined == false;
null == false;

It return false. W

Answer 1

According to the specification which was mentioned above:

If Type(y) is Boolean, return the result of the comparison x == ToNumber(y).

Number(undefined) = NaN;

false == NaN // false

Moreover if we change order false == undefined

If Type(x) is Boolean, return the result of the comparison ToNumber(x) == y.

Number(false) = 0;
0 == undefined

There is no rule for this case, so work the default behavior:

Return false.