Frequent Events, Listeners, and Handler Tests

Typing the word milk into a search box fires onChangeText four times, once for each letter. If each event started a network search, the app would send four requests, and three of the answers would be for text the user had not finished typing.

The previous lesson covered how to write a single handler. The habits here apply when events repeat quickly, when a listener must be removed by hand, and when a handler has several branches that need testing. As before, each example shows only its component. To run one, add the imports it uses and render it from App.