InstanceOf

• Action Code: 0x54
• Stack: 2 → 1
• SWF version: 6

ActionScript instanceof operator. Different from ECMA-262 (it supports interfaces).

Abstract AS2

@t0 = @pop();
@push(@pop() instanceof @t0);

Adobe documentation

ActionInstanceOf

ActionInstanceOf implements the ActionScript instanceof() operator. This is a Boolean operator that indicates whether the left operand (typically an object) is an instance of the class represented by a constructor function passed as the right operand.

Additionally, with SWF 7 or later, ActionInstanceOf also supports with interfaces. If the right operand constructor is a reference to an interface object, and the left operand implements this interface, ActionInstanceOf accurately reports that the left operand is an instance of the right operand.

Field	Type	Comment
ActionInstanceOf	ACTIONRECORDHEADER	ActionCode = 0x54

ActionInstanceOf does the following:

1. Pops constr then obj off of the stack.
2. Determines if obj is an instance of constr.
3. Pushes the return value (a Boolean value) onto the stack.