Creating strongly-typed event handlers

Interactive components need to handle events. In this lesson, we'll learn how to implement event handlers in a function component that has strongly-typed parameters. What we will learn also applies to class components as well.

Creating an inline anonymous event handler #

We are going to finish the implementation of a Searchbox component to learn how to strongly-type event handlers. Click the link below to open the exercise in CodeSandbox:

CodeSandbox project

The app contains an input that will eventually allow a user to enter some search criteria. At the moment, users can’t type anything into the input.

Let’s add an onChange event handler inline on the input that updates the criteria state:

<input
  type="text"
  value={criteria}
  onChange={e => setCriteria(e.currentTarget.value)}
/>

Notice that the editor provides IntelliSense on the e parameter. What is the type of e?

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