If we decide to delay the first process for a given amount of time to see if our user wants to type something else, so that if they do, we’ll cancel the first one and then work on the second instead, that would be debouncing. We’ll either have to prevent the second process from happening, or stop the first one and then start the second. This means that in our city filter, we won’t be able to ask our computer to filter out cities with “Sa” while it’s still trying to do the same thing for cities with “S” in their names. What’s debouncing and throttling?Īs you just saw in our city filter problem - where we’re asking our computer to start another process while it’s still trying to complete the previous one - debouncing and throttling are two different ways that we can prevent a function from running in multiple instances at the same time. #React keyup how to#Fortunately, there’s a way to solve our city filter problem, and in this article, we’re going learn how to do that in React, through debouncing and throttling. If we were, that’d be even more expensive and time-consuming. In our demo, we’re not making a server request to get our filtered cities. Same thing for “Sai”, etc., until we’re finished typing out “Saint Petersburg”. And while it’s still doing that, we ask it to look for all the cities with “Sa” in them. So when we type “S” in the input field, our computer tries to find all the cities that have the letter “S” in them. This is because our city list contains over 70,000 cities, so you can imagine how much work that is for our computer processor.Īs if filtering through this large list of data is not enough, we’re asking our computer to do this 16 times for the 16 keystrokes in the word “Saint Petersburg”. I have my virtual keyboard open, so you can see that I’m typing, but our input field stopped being responsive. In the demo above, I’m trying to search for a particular city in a large list of data. Here’s an example of when showing realtime search results as we type in an input field can make our computer unresponsive: This usually happens when there are event listeners attached to the actions being performed -like getting realtime results for a search query as you type, or fetching new posts or tweets on social media platforms while you’re still scrolling. Have you ever been in a situation where you’re typing in an input field and your computer or phone stops responding, or you’re scrolling through a webpage and it becomes unresponsive? How and when to debounce or throttle in React #React keyup software#Return keys.map(x => x.Ebenezer Don Follow Full-stack software engineer with a passion for building meaningful products that ease the lives of users. Window.removeEventListener(`keyup`, upHandler) Window.removeEventListener(`keydown`, downHandler) Cleanup our window listeners if the component goes away Window.addEventListener(`keyup`, upHandler) Window.addEventListener(`keydown`, downHandler) Which I do like this: const ALLOWED_KEYS = Ĭonst = eState()Ĭonst handleKeyDown = eCallback(event => ) // JS Objects are unique even if they have the same contents, this forces them to actually compare based on their contents It could also be that the 'state' is not updated properly. Then it seems like some keyup events aren't triggered. It's almost working as expected, except when I press a lot of the arrow keys at the same time. I've created a JSFiddle for my buggy component. Of course I'm trying to stay up to date with React so I wanted to create a function component and use hooks. I'm trying to create arrow based keyboard controls for a game I'm working on.
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