Examples

Usage is almost the same as set in the Dart's Window class and completely the same as described in the WHATWG HTML Standard. For each dialog there is just one file to import only the dialog you really need. There is also one file to import all four dialogs at once if you want to use them all.
import "package:dialog/~file~";

dialogs/alert.dart

Replaces default alert dialog.
querySelector("#alertButton").onClick.listen((_) {
  alert("Alerted?!");
});

dialogs/confirm.dart

Replaces default confirm dialog.
querySelector("#confirmButton").onClick.listen((_) async {
  var myConfirm = await confirm("Confirmed?!");
  alert(myConfirm.toString());
});

dialogs/prompt.dart

Adds missing prompt dialog.
querySelector("#promptButton").onClick.listen((_) async {
  var myPrompt = await prompt("Prompted?!", "Yes!");
  alert(myPrompt.toString());
});

dialogs/modal.dart

Adds fully customizable modal dialog.
querySelector("#modalButton").onClick.listen((_) async {
  var myModal = await modal(
      "Surprise", [Text("Boo!")], "Eek!", "Huh?", "Haha!", "Come on!", true);
  alert(myModal.toString());
});

dialog.dart

Do you need to use them all at once? Try to import dialog.dart file only!