I create 2 Text Boxes one with hook and the another one with the old style, now in Hook mode when the user input change the textbox value the whole page rendered, but with old style there only the text-box rendered not the whole page, if you have the complex page with many objects like (Data Table, form, buttons, inputs, etc..) the single change on one of these components forced to re-render everything and it decease performance, for example typing in the text-box take time to effect on page and the delay time is more than user typing speed.
the one workaround solution is using the callbacks and useMem but if the page is complex(lots of objects as described, and all of these objects has many properties the callback and useMem is very very complicated to handle single object property.
SandBox Example
This is exactly how react hooks should work. what will cause a rerender in react? two things:
change in props
change in hooks or say in a better way hooks state
in the second case, the useInput state is changing so that causes a rerender and it's absolutely normal behavior. I think using custom hook in that way is not a good practice.
I recommend reading this article for more information on react rendering: https://www.codebeast.dev/usestate-vs-useref-re-render-or-not/
Related
I am trying to use a parent component to control animations in a child Canvas element. Specifically I want an animation to happen when a user inputs a correct answer.
It works until the user changes the state in the parent component, and then it no longer works.
I've made a stripped-back, minimal version of my code here to show my issue: https://codesandbox.io/s/epic-leaf-08jqvy?file=/src/App.js
My desired behaviour is that the red box bounces when a user clicks submit. That happens if they don't type anything in the input box, but as soon as you enter anything into there - changing state and re-rendering the component - the button no longer triggers the animation in the Canvas child component.
As far as I can tell, the issue is to do with changing the state when inputing text. If I make a version where the input is just assigned to a variable, it works fine, but I need to be able to use state and re-render other parts of it.
I have put a console.log in the jump() function, so I can see that it is being called, but no animation is taking place in the canvas.
I assume that what's happening is that everything is being re-rendered when the state changes, and so the useRef is no longer tracking to the right thing.
Things I've tried:
putting the canvas in a memoized component to prevent it from re-rendering
using eventlisteners to see if I can trigger the animations in other ways - keydown ones work, but I need the user to be able to type, so I tried other ones (like hashchange or audio.play) but neither of those worked.
You can see the thing I'm actually trying to build here: https://papaya-platypus-86565f.netlify.app/play Basically users answer questions and an animation plays depending on whether they're right or wrong, to give it a game-y feel.
Thanks!
I like your red box as well as your reasoning. Yes, the input state changing on keystroke is causing the entire App component to re-render. Note that your App.js component has a lot going on (all good stuff), such as your Box class instantiation, your canvas instantiation, etc.
The key is to break your components into smaller parts, particularly separating stateful components from non-stateful components. We don't want your canvas re-mounting on every input change, so we make them sibling components!
Here's a working example of your code, just in smaller components:
https://codesandbox.io/s/strange-julien-d3n4zm
I hope this helps.
I'm trying to play an animation on dismounting of my component with exit attribute, but it doesn't work despite the presence of !
The input animation works fine but not the output one !
I guess I'm mismanaging the dismounting of my description which is displayed if the props data.show is true, boolean that I change at the click on the project, in short if someone can point me...
codesandbox
Thanks in advance
There are quite a few issues to cover in your code and suggest you first understand what triggers re-rendering in React.
By creating a new uuid key every time you change prop data, you are breaking the ability for React to know which components need to be rendered again so it re-renders them all - so it's always a new instance on AnimatePresence and no way for AnimatePresence to know there has been a change to the key or a change in mounting. Also make use of useCallback hooks when passing in functions to child components to avoid re-renders.
Move the state up to the parent, update the card key to a consistent value between renders, and don't update the entire props data just to expand/collapse.
See the updated sandbox
I suggest that you don’t animate multiple items inline within the same space like this as you will always have the remaining boxes jump a little, but that is another topic.
I'm using react-hooks. So there is a modal that pops up with a bunch of inputs (components) like text fields, drop-downs, date pickers and etc...
The problem is when some field is being edited, all my form components are being re-rendered and that makes my form very slow. I totally understand why it happens. However, I would like to find a way when I edit some input within my form, all other input fields (components) should stay "frozen" and not re-rendered. Otherwise, working with my form which has at least 20 input fields, would make the work very slow...
Your assistance is appreciated!
You can use Uncontrolled components. It doesn't use setState, so it won't be re-rendered when you type some input value. Then you can send everything when you submit your form.
Try using React.memo which is in some way an equivalent to shouldComponentUpdate
Check React.memo documentation
My page is composed of hierarchy of classes and many reusable components. Multiple instances of a button component can exist anywhere in the page and on click they fire actions that populate different types of data in a common sidebar list component.
The requirement is to highlight the button that was last clicked to load the data in that sidebar list. Of course, it also means to remove highlighting from the previous button. Since these button can exist in different components, I cannot manage state in one parent component.
I am not able to find a solution in pure React. I don't want to use jQuery rather just stick to React. Note I do use Redux in the app though and would be fine with leveraging Redux state if required.
You should most definitely use Redux. You'll need to create a variable in Redux that gets updated whenever an action takes place that would require you to highlight the button on the page. Then use conditional styling for the button based on that variable.
According to the docs, one should avoid having multiple components with state. I am in the situation where I want to make a text box that automatically expands vertically as the user writes, and for that I'm using this trick http://www.impressivewebs.com/textarea-auto-resize/, which means I need to get the height of a component. Now, I've been playing around with it a bit, and it doesn't seem feasible to pass a ref to my parent component which contains state, so the easy way out would be to keep a piece of state in the component with the textbox, and then use the ref from there.
This got me thinking, how exactly do multiple state components negatively affect my app? Is it only maintainability / comprehensability? Or are there actual performance issues with it? I've noticed a lot of open source react components that you would just plug in to your app keep state, meaning if you use open source components, chances are you will have several state components in your app.
It's totally ok to use local state for this kind of tricks on DOM. It's even better approach, than to share such implementation details to parent components.
In general, use this places for state:
Application-wide data in stores outside React (redux, flux-store, observables)
Form temporary data can be placed in store also. But if don't need it anywhere else except form, it's better to place this data in form component.
Tricks on DOM, short living and very local state can be placed in component that just need it
are there actual performance issues with it?
No. If you'll place all your state in components, your application will become even faster. Because when you update local state, only this component and it's childs updates.
But you shouldn't do that, because it kills maintainability.
lot of open source react components that you would just plug in to your app keep state
If component doesn't allow you to control it through the props - it's bad component. Usually open source components written to be easier to use, so they provide nice defaults, that allow you to just place component to your application, and be happy with that.
For example, Tabs component usually controlls selected tab using local state. But also it takes selectedTab and callback onSelect, so you can control it by yourself.
Stupid components (like your textarea component) should not have state with data. But they can have their own UI state.
In this case you can easily keep textarea height in state of stupid component.