We've been using redux-form and seeing a noticeable lag when user types in an input field. I'm not really sure if it's a problem with redux-form. This could probably be the way we've structured our components. So we have page which lists some data, say 25 rows and filters for it. On click of a button, we open a modal where we render a redux-form. Now if user types in any of the input field, all the list items in the underlying page also get re-rendered. We're using React.Component for list items. React devtool's "Highlight updates" option highlights list items but when I do a console.log in list item's render method, it's not printing!
Wonder if this is happening because the list item's parent component is also a (redux) connected component and when redux-form's Field updates the store, this also gets re-rendered? How do you use redux-form in such scenario? I don't think having multiple stores is a recommended way.
I'm guessing you have an event listener for when any of the inputs on the form changes, and then you do some fetching/filtering on the underlying list?
Running this when typing quickly could lead to a performance hit, depending on what your event listener does. You could try using something like lodash.debounce to only run your listener after the user has stopped typing for like 200ms?
Related
I want to build a simple app like in picture attached with react js, I just cannot find the right idea of:
How to "select" photos(or item) in an application and have the "cart"-like component appear at the bottom when at least one photo/item is selected(and close and deselect all already selected photo/items) and expand the cart-like component at the bottom when clicked to show what's been already selected.
What is the best approach to this?
P.S I'm new to react with a big idea in mind xD
app's view
This question definitely needs more information, but I will try to point you in the right direction. There are hundred of ways to create the UI/functionality you are describing but here is a very generic overview;
The "items" (Img1-6) looks like a grid of ShopItem components, possibly in a CSS Grid / flexbox. Each ShopItem would probably make use of an onClick method to "do something" when it is clicked - this may involve updating a state (using the useState react hook) somewhere which tells you if a ShopItem is checked or not. It could also potentially use a callback method to do something in the parent when the items are checked.
I imagine that each ShopItem may own its own "checked" state or may update a global state (Such as Zustand or Redux) or a Context (React) when it is toggled on and off. The checked state of a ShopItem would also inform the UI of the component.
The "cart-like" component could be looking at the global state/context/callback from the item component, and could change based on its value and how many checked items there are. (Eg/ checkedItems !== 0 ? show : don't show)
This is just one way in which this UI can be built, if you would like a more specific solution, please edit your question to include code snippets and what you've already tried.
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/
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.
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
In react-table, I've made a custom drop-down-menu component that appears when user clicks on a header of a column.
When user clicks on the option "Choose columns", a modal appears with checkboxes options where user can select which columns to show or hide.
This modal with the checkboxes options is in the drop-down-menu component. The problem is I can not figure out which is the best way to handle state changes. Should I keep state changes on both components (table component and drop-down-menu component)? Should I use redux for that? I'm going to use many tables, so the total number of columns will be very big. I'm really confused about all this.
You should have one source of truth. As the table will need this information, it should be saved in the table and passed to the drop-down-menu component.
Checkout this codesandbox example.
Well if you want to make your checkbox reusable component, which you should, then you will have to keep the state in your checkbox component and expect an onChange event handler from wherever you want to use that checkbox component.