![]() This also takes into account any modifier keys that might have affected the KeyboardEvent. ![]() KeyboardEvent.key is a read only property that returns a String that is set to the current key that was pressed.KeyboardEvent.repeatis a read only property that returns a Boolean that is set to true if the key is being held down such that it is automatically repeating.While there are many properties, we will only be focused on two specific properties. This will call our listener function with a KeyboardEventwhich has a number of properties that will allow us to build our custom hook. To listen for keypresses in our application, we will be registering and event listen for the keydown/keyup events. If we do not do this, React will re-instantiate a new function every time our custom hook re-renders, which will happen quite often. useCallback is simply a performance optimization hook which we use to wrap our event listener callback function.We will use a keydown event to keep track of held down keys and a keyup event to keep track of released keys. useReducer allows us to keep a state of pressed keys.It will also remove listeners when the component unmounts. In our specific case, we will use this hook to create an event listeners when our component mounts. useEffect allows us to add side effects to our application.Similar to Step 1, we can still take advantage of useEffect to run things in the browser, such as adding event listeners.In order to properly implement this functionality, we'll be using a combination of three hooks: Taking this a step further, we may want to broadly listen for events, such as someone using a keyboard or resizing their browser window, where we wouldn’t have access to a ref that would make sense in that case. So now, instead of the console.log statement, add: () Focused search inputĪnd if you reload the page, as soon is it loads, the input will be focused!įollow along with the commit! Step 2: Listening for keyboard events in React ![]() That means, we have access to our native DOM APIs! Dev tools showing an input logged to the console If we look inside of our browser and look at the dev tools, we should now see that we’re logging out our input element. It will only run once because we’re passing in an empty array, which tells React it should run, but it doesn’t have any dependencies we want to listen to changes on. This will run the function inside of the useEffect hook once after the first render of the component. Scroll down to the form on the page, where inside there will be an input with the name of “query”. Then we’ll want to associate our ref with the element. Note: if you’re following along with the SWAPI example, it’s a good idea to put the ref below hasResults to avoid ordering issues later. At the top of the component in the same index.js file, add: const inputRef = useRef() While it involves much more than that, generally that listener could look like: document.querySelector('#my-button').addEventListener('click', () => from 'react' To do this in JavaScript, we generally select the element we want to listen “on” and what event we want to listen for. When that happens, you could be validating that input to make sure it’s well, valid. Or maybe you’re listening for the content of an input to change. ![]() Maybe you have a button that you want to do something special. Most of those interactions trigger “events” where in JavaScript, we have the ability to listen for those events, and subsequently do something whenever we detect that one of those events occurred.Ī super common event is listening for a click.
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