a == true is a loose comparison, so the Machine will convert the “x” type to String and then evaluate.

a === true is a strict comparison, so the Machine will actually check if the type is the same first.

if(a) is a little different, as it will return true if the object is not:

- null;
- undefined;
- false;
- evaluates to false, like ” or 0;

The latter statement is usually used to check if something exists, but it’s dirty, and AS3 gives us new means of checking if a variable exists and if it is populated.

At least, I think.. :P

That is wrong. Try class A and class B both have toString returning the same. Anyways if you just try something like trace( a == b ); you get a compile-time error because comparison of two different types is made.

Also if you want to compare a to ” and toString() returns ” you get the same error.