How to perform runtime type checking in Dart?

The instanceof-operator is called is in Dart. The spec isn't exactly friendly to a casual reader, so the best description right now seems to be http://www.dartlang.org/articles/optional-types/.

Here's an example:

class Foo { }

main() {
  var foo = new Foo();
  if (foo is Foo) {
    print("it's a foo!");
  }
}

Dart Object type has a runtimeType instance member (source is from dart-sdk v1.14, don't know if it was available earlier)

class Object {
  //...
  external Type get runtimeType;
}

Usage:

Object o = 'foo';
assert(o.runtimeType == String);

As others have mentioned, Dart's is operator is the equivalent of Javascript's instanceof operator. However, I haven't found a direct analogue of the typeof operator in Dart.

Thankfully the dart:mirrors reflection API has recently been added to the SDK, and is now available for download in the latest Editor+SDK package. Here's a short demo:

import 'dart:mirrors'; 

getTypeName(dynamic obj) {
  return reflect(obj).type.reflectedType.toString();
}

void main() {
  var val = "\"Dart is dynamically typed (with optional type annotations.)\"";
  if (val is String) {
    print("The value is a String, but I needed "
        "to check with an explicit condition.");
  }
  var typeName = getTypeName(val);
  print("\nThe mirrored type of the value is $typeName.");
}