Suppose we’d like to invoke the JavaScript function JSON.stringify which receives an object, encodes it into a JSON string and returns it.

All we’d have to do is write the function signature, mark it as external and annotate it with the @JS annotation:

@JS("JSON.stringify")
external String stringify(obj);

The @JS annotation will be used from here on out to mark Dart classes that we’d like to use in JavaScript as well.