By now you've probably seen that typing in values within fields fires off a field event. This is evident in fields that are shown in the web part, as each update to the field text forces an update on the text being displayed.
By changing the Description Field in our sample, the same text is being reflected within the web part canvas on the left:
This is called a reactive mode, and it simply forces the web part to update the user interface whenever the property field values are updated.
An alternative to this is the non-reactive mode, which might be useful in certain scenarios.
Reactive mode is especially useful for text-based data, but might be problematic if a change fires off a chain of events that might be time-consuming. Updating a simple field value would take a longer time if our code insists on updating content after each key click.
As the property pane is in reactive mode by default, changing to the non-reactive mode is simple. All you need...