Trigger reactions with observeEvent()

There are times when you want to perform an action in response to an event. For example, you might want to let the app user download a table as a CSV file, when they click on a "Download" button. Or, you might want to display a notification or modal dialog, in response to a click.

The observeEvent() function allows you to achieve this. It accepts two arguments:

The event you want to respond to.
The function that should be called whenever the event occurs.

In this exercise, you will use observeEvent() to display a modal dialog with help text, when the user clicks on a button labelled "Help". The help text has already been assigned to the variable bmi_help_text.

UI:
- Add an action button named 'show_help', labelled "Help". You might have to scroll down or collapse the console to view the UI.
Server:
- Uncomment the code # showModal ...
- Wrap showModal(...) in observeEvent() so that the help text is displayed when a user clicks on the help button

Take Hint (-30 XP)

Exercise

Trigger reactions with observeEvent()

Instructions