I am currently using ant design tabs to control the tabs and within each tab I inserted a custom component within the TabPane. But the child custom component works quite unexpected. Before I clicked the tab title, the child component will not load (the constructor and componentDidMount will not be fired), BUT I want to load some data once the child component mounted to the tab instead of being shown.
Why it happened? ~~Ant Design~~ for performance concern?
Currently I am moving the data loading to the parent and handle them there. But still quite curious about the loading issue caused by ant design.
Related
I am using a button to display a modal for a particular profile (different buttons for different profiles). By using a hook, the modal just renders the last profile's info. (I am mapping the profile info list)
Is there a way I can call the modal component in the mapping itself without using Hook? Or any different approach to this problem?
(P.S the code is too long, hence not pasting it in the question description)
I wired up parent and modal using another component in between, and it worked.
I created a component receiving props(containing profile info) from parent and passing it to the modal. And the modal is called from the parent via this new component.
I have a TabView component that has multiple tabs containing components. These components have entire hierarchies of other components. How could I know from any child component nested arbitrarily deep in one of these hierarchies whether or not it's parent tab is in focus in the TabView?
Preferably, I would want to implement this similar to react-navigation's withNavigationFocus (or an equivalent hook) so that any component can know if it's in tab focus without having to pass props down the chain of components. I'm thinking you could have a TabViewContext that components can register themselves as focus listeners to by doing a useContext. The TabViewContext would be provided by the TabView and the TabView would be responsible for determining what registered listeners are in focus when tabs change. My dilemma is I don't know how the TabView could determine efficiently what nested child components come into focus when the tab changes. Any ideas?
In case the other parent tabs are hidden, you could test for visibility in plain JS, rather than have a much more complex solution...
Checkout this answer on how to do this.
So components that care about the visibility of their parent tab could use a ref for their own DOM elements and test whether they're visible or not. You could build this into a simple helper function or a hook
EDIT:
I'd suggest going with something like this:
Each Tab will provide a context with method for any descendant to register a callback that will be called when the Tab is hidden. The TabView can pass a "isVisible" prop to each tab (if it doesn't already), so Tab can know when its display changes.
When a Tab changes from visible to hidden. All registered callbacks will be called.
I would of course write a hook or a helper function to create this TabVisibilty context so each Tab component can use it in a reusable manner.
I have 3 components:
Parent
Form
Preview
With every change on Form Component, I pass the values to Parent, from Parent to Preview component. And it works.
The problem is when I change values on Form, the Preview component show like a flicker (because it's re-rendering the preview component). How can avoid this?
Maybe not updating preview component for every small change? How can I do it?
Component diagram:
In my React app, I have tabs at the top of the app, a sidebar for navigation and a section to the right of the sidebar, and below the tabs that show content. When the user clicks on a tab, the sidebar loads its navigation data from the backend. Then after loading it, by default it selects the first item in the sidebar and loads the content details. The content details are made up of different components and several backend calls may need to be made.
What I would like to do is display a progress bar just above the tabs which is shown the moment the user clicks on the tab. The progress bar is only dismissed after the entire content for both the sidebar and content details has been loaded. The sidebar and content details do not update or are even shown until they have completely retrieved all their data from the backend and done any other initialization.
Determining exactly when all the content has been loaded is tricky as each component in the sidebar and content details are responsible for retrieving data from the backend. The only solution I could think of is for each component to implement a publisher/subscriber mechanism. Each parent component notifies each child component that it needs to load its data. When the child component receives this notification and has retrieved its data from the backend and finished any other initialization, it then notifies the parent that it has completed. Only when the top-level component gets all notifications from all its direct children, does it then dismiss the progress bar and cause the content to be displayed.
Another possible approach is to have only the first child component retrieve all the data from the backend on behalf of all the descendent components and cache it in the local repository. This would eliminate the need for descendent components from having to call the backend and could quickly just retrieve the data from the local repository. But there is still the issue of initializing each nested component. If I show the entire content while it is still in the initialization phase, the user would notice this. Still, I suspect React renders most stuff so fast that users will probably not notice it.
I'm not sure if this is the approach I should be taking or if there is something more inherent in React that handles this.
A similar website where you can see this is at Google's:
https://fuchsia.dev
although this site probably has much fewer backend calls than the one I am working on. But in general, this is close to what I am looking to achieve.
Your solution with the subscriber pattern will work fine, but if you want something less complex, there are two common approaches:
If you are using redux, every child component dispatches that it is loading data right now with their unique id. When it finishes (or component is unmounted), it dispatches an action to remove the loading information. Parent component just checks redux store, if there is anything loading.
The second approach without redux is to pass a callback to the child components from the parent through props. This callback expects two parameters: unique id and bool value representing if the child components starts/finishes loading. When the child component starts loading, it calls the callback from the parent with a unique id and value true. When the child component finishes loading, it calls the callback again with the same unique id and value false. Parent component set to its state which child components are loading and renders the loading accordingly.
I've got an app that shows a list of items in a grid. Some of the items have an embedded video which flashes or stops playing (if it's already playing) when it's rerendered.
The list is maintained in Redux. When the user scrolls to the bottom of the page it loads more results which causes the Redux state to update which, in turn, causes the grid to rerender all of the items plus the new items.
I'm looking for a solution that will just add more items to the end of the grid instead of rerendering everything.
I've got a component that holds the entire grid. It renders a component for each item in the grid. In each item I have a component that holds the embedded video.
Any ideas?
If each item in the grid is a component, like you said, you should use React.memo (for functional compoents) or Reat.PureComponent (for class components). It will prevent the component from rerendering if the props have not changed. I can't guarantee your videos will keep playing, but if the only reason they stop playing or flash is because the component is being rerendered then it should fix the problem.
Maybe this can help: when passing information from redux to your component, try to update the list of the objects instead of sending a new one
It's redux UpdateObject method.