TLDR Version: React defines the property "isReactComponent" in its "Component" class prototype object. When you extend "Component" React can simply check "MyCla

TLDR Version: React defines the property "isReactComponent" in its "Component" class prototype object. When you extend "Component" React can simply check "MyClass.prototype.isReactComponent" and if the result is true, it knows it's a class and not a function!