node_modules/aurelia-templating-router/dist/aurelia-templating-router.js
// animate the next view in before removing the current view;
animate the next view in before removing the current view.
animate the next view in before removing the current view .
before(viewSlot, previousView, callback) {
    let promise = Promise.resolve(callback());
    if (previousView !== undefined) {
      return promise.then(() => viewSlot.remove(previousView, true));
    }
    return promise;
  }
before ( viewSlot , previousView , callback ) { let promise = Promise . resolve ( callback ( ) ) ; if ( previousView !== undefined ) { return promise . then ( ( ) => viewSlot . remove ( previousView , true ) ) ; } return promise ; }
animate the next view in before removing the current view;
animate the next view in before removing the current view ;