It will fire when either one changes. The way to think of it is that you are telling React: a and b are the things that I am using inside this effect, so if either of them change, my effect will need to cleanup the old version and re-execute with the updated values. Here’s a … Read more
anchorEl variable is ref object, an object that has only current property. It’s unknown how Popover works but, but it expects an element as anchorEl prop, not a ref. It should be: <Popover id=”simple-popper” open={open} anchorEl={anchorEl.current} If <Popover and <div ref={anchorEl} > are siblings like it’s shown, a ref won’t be ready to use at … Read more
That is correct. They will do basically the same thing. In my opinion, the useContext hook has a much nicer and readable syntax. From React Docs: https://reactjs.org/docs/hooks-reference.html#usecontext useContext const value = useContext(MyContext); Accepts a context object (the value returned from React.createContext) and returns the current context value for that context. The current context value is … Read more
The issue is that upon each render cycle, markup is redefined. React uses shallow object comparison to determine if a value updated or not. Each render cycle markup has a different reference. You can use useCallback to memoize the function though so the reference is stable. Do you have the react hook rules enabled for … Read more
The type that would match the function returned from invoking useState would be: setMyVar: (value: boolean | ((prevVar: boolean) => boolean)) => void; If we look at the type definition file from DefinitelyTyped [1], we can see that the second type in the return type is a dispatch: function useState<S>(initialState: S | (() => S)): … Read more
It’s because the react-router context isn’t set in that component. Since its the <Router> component that sets the context you could use useHistory in a sub-component, but not in that one. Here is a very basic strategy for solving this issue: const AppWrapper = () => { return ( <Router> // Set context <App /> … Read more
You should not set state (or do anything else with side effects) from within the rendering function. When using hooks, you can use useEffect for this. The following version works: import React, { useState, useEffect } from “react”; import ReactDOM from “react-dom”; const StateSelector = () => { const initialValue = [ { id: 0, … Read more
useRef is just partially similar to React’s ref(just structure of object with only field of current). useRef hook is aiming on storing some data between renders and changing that data does not trigger re-rendering(unlike useState does). Also just gentle reminder: better avoid initialize hooks in loops or if. It’s first rule of hooks. Having this … Read more
NOTE: you better start using redux-toolkit to prevent references in you code its a better and almost a must way for using redux the problem your facing is very common when handling with objects, the props do not change because you’re changing an object property but the object itself does not change from the react … Read more
The problem can be found in your onClick prop: <button className=”previous-round” onClick={setOrderData_(previous(orderData_))}>‹</button> ^ Everything between the curly braces gets evaluated immediately. This causes the setOrderData_ function to be called in every render loop. By wrapping the function with an arrow function, the evaluated code will result in a function that can be called whenever the … Read more