Type test operators
The as, is, and is! operators are handy for checking types at runtime.
| Operator | Meaning |
as | Typecast (also used to specify library prefixes) |
is | True if the object has the specified type |
is! | True if the object doesn't have the specified type |
The result of obj is T is true if obj implements the interface specified by T.
Use the as operator to cast an object to a particular type if and only if you are sure that the object is of that type.
(employee as Person).firstName = 'Bob';
If you aren't sure that the object is of type T, then use is T to check the type before using the object.
if (employee is Person) {
// Type check
employee.firstName = 'Bob';
}