This is my navbar component. Exports a memoized one.
import * as PropTypes from 'prop-types';
import Style from './Navbar.module.scss';
import NavbarItem from './NavbarItem';
import React from 'react';
/**
* #param items
* #param type
*/
export default function Navbar({ items }) {
return (
<nav className={Style.main}>
{items.map((item, i) => (
<NavbarItem name={item.name} url={item.url} items={item.items} key={item.name + i} />
))}
</nav>
);
}
export const MemoizedNavbar = React.memo(Navbar, true);
Navbar.propTypes = {
items: PropTypes.array.isRequired,
type: PropTypes.string,
};
Header that uses the Navbar.
import React, { Fragment, useContext } from 'react';
import Logo from './Logo';
import { MemoizedNavbar } from '../Navbar/Navbar';
import Style from './Header.module.scss';
import { ListContext } from '../../lib/Context/ListContext';
import BrandsHelper from '../../lib/List/BrandsHelper';
import { Items } from '../../config/SiteNavbar';
import Svg from '../Utils/svg';
const {useState} = require("react");
export default function Header({ brand }) {
const [lists, setLists] = useContext(ListContext);
const listData = lists.lists[lists.currentListId];
const [hamburgerMenuOpen, setHamburgerMenuOpen] = useState(false);
const handleHamburgerClick = () => {
setHamburgerMenuOpen(!hamburgerMenuOpen);
}
return (
<header className={Style.header}>
<section className={Style.section}>
<Logo brand={brandName} />
<MemoizedNavbar items={Items} />
<button className={Style.hamburgerButton} aria-label="Menu" onClick={handleHamburgerClick}>
<span className={Style.hamburgerButtonClickable} />
</button>
</section>
</header>
);
}
When I click in the HambugerButton, I get the following error:
If I don't use the Memoized component, it works just well.
What could be wrong?
export const MemoizedNavbar = React.memo(Navbar, true);
The second argument is expected to be a function, like:
function areEqual(prevProps, nextProps) {
/*
return true if passing nextProps to render would return
the same result as passing prevProps to render,
otherwise return false
*/
}
If you don't need to do anything particular, just drop the second argument, and react will do a shallow comparison.
export const MemoizedNavbar = React.memo(Navbar);
Related
I'm currently coding a React -typescript App for practising FluentUI (a.k.a Fabric). Issue appears
with my App.tsx component.
import React, { useContext, useState } from 'react';
import logo from './logo.svg';
import './App.css';
import Search from './components/Search';
//import CategoriasProvider from './components/Context/CategoriasContext';
import Title from './components/Title';
import { ListGhostingExample } from '../src/components/DrinkList';
import { PrimaryButton } from 'office-ui-fabric-react';
import { CategoriasContext, ICategoriasContextInterface } from './components/Context/CategoriasContext';
import CategoriasProvider from './components/Context/CategoriasContext';
import axios from 'axios';
import './components/DrinkList.css'
import './components/Search.css'
interface IApp{
items:ICategoriasContextInterface[],
renderList:boolean
}
const App =()=> {
const contextValues=useContext(CategoriasContext);
return(
<CategoriasProvider>
<div className="App">
<div className="search">
<Search name={contextValues?.name} image={contextValues?.image} thumbnail={contextValues?.thumbnail} />
</div>
</div>
</CategoriasProvider>
);
}
export default App;
CategoriasProvider comes from a Context (CategoriasContext.tsx ). CategoriasProvider has the mentioned error Inside of CategoriasProvider there's a Search.tsx Component.Search's works as a "wrapper". Code is:
import React, { useEffect, useState } from 'react';
import { SearchBox,ISearchBoxStyles } from 'office-ui-fabric-react/lib/SearchBox';
import { PrimaryButton, IContextualMenuProps, Stack, IStackTokens, StackItem, initializeIcons } from 'office-ui-fabric-react';
import { ComboBox, DefaultPalette, Dropdown, DropdownMenuItemType, IComboBoxOption, IDropdownOption, IDropdownStyles, IStackItemStyles, SelectableOptionMenuItemType, Toggle } from '#fluentui/react';
import { getGlassesOriginal } from './Utils/Utils';
import axios from 'axios';
import '../Search.css';
import { CategoriasContext, ICategoriasContextInterface } from './Context/CategoriasContext';
initializeIcons();
const Search = (props:ICategoriasContextInterface) => {
//State
const [textContent, setTextContent] = useState("");
const [textBoxDisabled,disableTextBox]=useState(false);
const [comboBoxDisabled,disableComboBox]=useState(true);
const CategoriasContextInSearch=React.useContext(CategoriasContext);
const setTextContentInstate = (e: any) =>{
console.log("Contenido de e" + e.target.value);
setTextContent(e.target.value);
}
const showMessageInConsole = ():void => {
console.log(textContent);
setTextContent("");
}
// Example formatting
const stackTokens: IStackTokens = { childrenGap: 20 };
const searchBoxStyles: Partial<ISearchBoxStyles> = { root: { width: 200 } };
const dropdownStyles: Partial<IDropdownStyles> = {
dropdown: { width: 200 },
};
const options: IDropdownOption[] = [
{ key: 'glasses', text: 'Glasses', itemType: DropdownMenuItemType.Header },
];
function getGlasses () {
let outputArray:string[] = [];
console.log("getGlasses");
axios
.get("https://www.thecocktaildb.com/api/json/v1/1/list.php?g=list")
.then((response)=>{
let responseDataJson=response.data.drinks;
for (let element in responseDataJson) {
options.push({key:responseDataJson[element].strGlass,text:responseDataJson[element].strGlass});
}
}
)
return outputArray;
}
function selectSearch(){
if(textBoxDisabled){
disableTextBox(false);
disableComboBox(true);
} else {
disableTextBox(true);
disableComboBox(false);
};
}
useEffect(() => {
//TODO: No se debería llamar siempre a esta función. Solamente cuando se activa el sistmea de búsqueda (y además, cachearlo)
getGlasses()
});
return(
<div className="wrapper">
<div className="one"> <Toggle onClick={selectSearch}/></div>
<div className="two">
{
<SearchBox
name="searchBox"
className="searchBox"
styles={searchBoxStyles}
placeholder="Cheers!"
onChange={setTextContentInstate}
value={textContent}
disabled={textBoxDisabled}
/>
}
</div>
<div className="three">
<Dropdown
placeholder="Select a glass"
options={options}
styles={dropdownStyles}
disabled={comboBoxDisabled}
/>
</div>
<div className="four">
<div className="primaryButton">
<PrimaryButton text="Search" onClick={showMessageInConsole}/>
</div>
</div>
</div>
);
}
export default Search;
Hope you can help me!!! Thanks in advance!
The code which is causing the error in your title is in your comment. It's this line:
export const CategoriasProvider = () => {
You are defining CategoriasProvider as a component which takes no props. It can only accept IntrinsicAttributes which is basically just the key property.
But when you use CategoriasProvider in App you are calling it with JSX element children. You get an error because you have not said that the CategoriasProvider component can accept a children prop.
Any of the following types will solve your problem:
export const CategoriasProvider: React.FC = ({children}) => {
export const CategoriasProvider = ({children}: {children: React.ReactNode}) => {
export const CategoriasProvider = ({children}: React.PropsWithChildren<{}>) => {
Regardless, you'll want to pass the children down as children of the inner Provider component.
return (
<CategoriasContext.Provider value={hola}>
{children}
</CategoriasContext.Provider>
);
Your App component is not going to work as expected because the useContext hook which accesses the CategoriasContext is located outside of the CategoriasProvider. It will just get the default value for the context -- not the value from the provider.
You need to rearrange your components such that the hook call occurs in a component that is rendered inside of the CategoriasProvider.
Try this:
const Search = () => {
const contextValues = useContext(CategoriasContext);
return (
<div className="search">
<Search
name={contextValues?.name}
image={contextValues?.image}
thumbnail={contextValues?.thumbnail}
/>
</div>
);
};
const App = () => {
return (
<CategoriasProvider>
<div className="App">
<Search />
</div>
</CategoriasProvider>
);
};
export default App;
I've got a few React functional Components that I would like to share a state. In this example two toggle buttons that would conditionally show/hide a searchbar and a navbar.
--Solution, based on the accepted answer, on the bottom--
I'm completely new to useContext() and I keep running into the following error in the console:
Uncaught TypeError: setSearchbarToggle is not a function This goes for both buttons.
Bellow I have a filtered example code. It is just for the example I use the states in one file. In real life I would re-use the states in multiple functional components.
This is my header.js
import React, { useState, useContext } from "react"
import "./header.sass"
import { Context } from "./HeaderContext"
export const Header = () => {
const headerContext = useContext(Context)
const { navbarToggle, setNavbarToggle, searchbarToggle, setSearchbarToggle } = headerContext
return (
<React.Fragment>
<div className={"sticky-top"}>
<button onClick={ () => setNavbarToggle( !navbarToggle )}> Toggle Menu </button>
<button onClick={ () => setSearchbarToggle( !searchbarToggle )}> Toggle Search </button>
{navbarToggle && <h3>Menu is showing</h3>}
{searchbarToggle && <h3>Searchbar is showing</h3>}
</div>
</React.Fragment>
)
}
export default Header
And this is my HeaderContext.jsx
import React, { createContext, useState } from "react";
import PropTypes from "prop-types";
export const Context = createContext({});
export const Provider = props => {
const {
navbarToggle: initialNavBarToggle,
searchbarToggle: initialSarchbarToggle,
children
} = props;
const [navbarToggle, setNavbarToggle] = useState(initialNavBarToggle);
const [searchbarToggle, setSearchbarToggle] = useState(initialSarchbarToggle);
const headerContext = {
navbarToggle, setNavbarToggle,
searchbarToggle, setSearchbarToggle
};
return <Context.Provider value={headerContext}>{children}</Context.Provider>;
};
export const { Consumer } = Context;
Provider.propTypes = {
navbarToggle: PropTypes.bool,
searchbarToggle: PropTypes.bool
};
Provider.defaultProps = {
navbarToggle: false,
searchbarToggle: false
};
I hope you can shed some light on this for me
--edit--
This is my code based on the accepted answer.
import React, { useContext } from "react"
import { Provider,Context } from "./HeaderContext"
export const HeaderWithContext= () => {
const headerContext = useContext(Context)
const { navbarToggle, setNavbarToggle, searchbarToggle, setSearchbarToggle } = headerContext
return (
<React.Fragment>
<div className={"sticky-top"}>
<button onClick={ () => setNavbarToggle( !navbarToggle )}> Toggle Menu </button>
<button onClick={ () => setSearchbarToggle( !searchbarToggle )}> Toggle Search </button>
{navbarToggle && <h3>Menu is showing</h3>}
{searchbarToggle && <h3>Searchbar is showing</h3>}
</div>
</React.Fragment>
)
}
export const Header = () => {
return (
<Provider>
<HeaderWithContext/>
</Provider>
)
};
One of the parent components, e.g. App, must wrap the header (or one of its ancestor components) with Context.Provider:
import { Provider } from "./HeaderContext"
...
<Provider>
<Header />
</Provider>
Why is useContext undefined?
Context
import React from 'react'
const PathContext = React.createContext()
export default PathContext
from a jsx file
import PathContext from '../../../contexts/pathContext';
.......
<PathContext.Provider
value={{
paths,
pathChecks
}}
>
<MyComponent />
</PathContext.Provider>
In MyComponent.jsx render function..
import PathContext from 'path/to/file';
import {useContext} from 'react';
const {
paths,
pathChecks
} = useContext(PathContext);
UNDEFINED!
What is my context undefined?
Use it like so:
App.js (or Main Component)
// App.js
import React from "react";
import MyContext from "./PathContext";
import MyComponent from "./MyComponent";
export default function App() {
return (
<div className="App">
<MyContext>
<MyComponent />
</MyContext>
</div>
);
}
PathContext.js
// PathContext.js
import React, { createContext } from "react";
export const PathContext = createContext(); // regular export
// A new component that will hold the context values and will wrap your <MyComponent>
const MyContext = ({ children }) => {
const paths = "define your paths";
const pathChecks = "define your pathChecks";
return (
<PathContext.Provider
value={{
paths,
pathChecks
}}
>
{children} // Pass children props
</PathContext.Provider>
);
};
export default MyContext; // default export MyContext component
MyComponent.js (context consumer)
// MyComponent.js
import React, { useContext } from "react";
import { PathContext } from "./PathContext";
const MyComponent = () => {
const { paths, pathChecks } = useContext(PathContext);
return (
<div>
<div>{paths} value</div>
<div>{pathChecks} value</div>
</div>
);
};
export default MyComponent;
Here is a sandbox example.
I think you need to use {useContext} from 'react' instead of {useContext} from React
Please check this example. It is working fine.
import React, {useContext, useEffect, useReducer, useState} from 'react';
import PathContext from "./PathContext";
function PathContextExample() {
const paths = 'this is path';
const pathChecks = 'this is path checks';
return (
<div>
<PathContext.Provider
value={{
paths,
pathChecks
}}
>
<MyComponent/>
</PathContext.Provider>
</div>
)
}
export default PathContextExample;
function MyComponent() {
const {
paths,
pathChecks
} = useContext(PathContext);
return (
<div>
{paths}
<br/>
{pathChecks}
</div>
)
}
In MyComponent.jsx file you should import PathContext
i'm trying to only render the component <IntercomClient /> after a user clicks "Accept" on a cookie consent banner. Clicking accept changes the GlobalLayout's intercomIsActive state to true and thereby renders the IntercomClient. This is working but the warning concerns me.
How can I workaround the child/parent state change? I've been looking around but don't really understand.
import React, { useState } from 'react'
import { CookieBanner } from '#palmabit/react-cookie-law'
import IntercomClient from '../components/intercomClient'
const GlobalLayout = ({ location, children }) => {
const [intercomIsActive, setIntercomIsActive] = useState(false)
return (
...
<CookieBanner
onAccept={() => setIntercomIsActive(true)}
/>
<IntercomClient active={intercomIsActive}/>
...
)}
IntercomClient
import React from 'react';
import Intercom from 'react-intercom'
const IntercomClient = ({ active }) => {
return active ? <div><Intercom appID="XXXXXX" /></div> : null
}
export default IntercomClient;
import React, {useState} from 'react';
const Example = () => {
const [intercomIsActive, setIntercomIsActive] = useState(false)
return (
<Layout>
...
<CookieBanner
onAccept={() => setIntercomIsActive(true)}
/>
<IntercomClient active={intercomIsActive}/>
...
</Layout>
);
};
export default Example;
import React, {useState} from 'react';
const Example = () => {
const [intercomIsActive, setIntercomIsActive] = useState(false)
return (
<Layout>
...
<CookieBanner
onAccept={() => setIntercomIsActive(true)}
/>
{
intercomIsActive &&
<IntercomClient active={intercomIsActive}/>
}
...
</Layout>
);
};
export default Example;
I'm trying to use React Context to update navbar title dynamically from other child components. I created NavbarContext.js as follows. I have wrapped AdminLayout with NavContext.Provider and use useContext in Course.js to dynamically update navbar title inside useEffect. However, when I'm doing this, react throws the following error on the screen.
Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.
How can I use context properly so that I can update Header title from Course.js inside its useEffect?
NavbarContext.js
import React, {useState} from 'react'
export default () => {
const [name,setName] = useState("")
const NavContext = React.createContext({
name: "",
changeName: name => setName(name)
})
const NavProvider = NavContext.Provider
const NavConsumer = NavContext.Consumer
return NavContext
}
AdminLayout.js
<NavContext.Provider>
<div className={classes.wrapper}>
<Sidebar
routes={routes}
logoText={"Widubima"}
logo={logo}
image={image}
handleDrawerToggle={handleDrawerToggle}
open={mobileOpen}
color={color}
{...rest}
/>
<div className={classes.mainPanel} ref={mainPanel}>
<Navbar
routes={routes}
handleDrawerToggle={handleDrawerToggle}
{...rest}
/>
{/* On the /maps route we want the map to be on full screen - this is not possible if the content and conatiner classes are present because they have some paddings which would make the map smaller */}
{getRoute() ? (
<div className={classes.content}>
<div className={classes.container}>{switchRoutes}</div>
</div>
) : (
<div className={classes.map}>{switchRoutes}</div>
)}
</div>
</div>
</NavContext.Provider>
Navbar.js
import NavContext from "context/NavbarContext"
export default function Header(props) {
function makeBrand() {
var name;
props.routes.map(prop => {
if (window.location.href.indexOf(prop.layout + prop.path) !== -1) {
name = prop.name;
document.title = name;
}
return null;
});
return name;
}
return (
<AppBar className={classes.appBar + appBarClasses}>
<Toolbar className={classes.container}>
<div className={classes.flex}>
{/* Here we create navbar brand, based on route name */}
<NavContext.Consumer>
{({ name, setName }) => (
<Button
color="transparent"
href="#"
className={classes.title}
style={{ fontSize: "1.5em", marginLeft: "-2%" }}
>
{makeBrand() || name}
</Button>
)}
</NavContext.Consumer>
</Toolbar>
</AppBar>
);
}
Course.js
import React, { useState, useEffect, useContext } from "react";
import NavContext from "context/NavbarContext"
const AdminCourse = props => {
const context = useContext(NavContext);
useEffect(() => {
Axios.get('/courses/'+props.match.params.courseId).then(
res => {
context.changeName("hello")
}
).catch(err => {
console.log(err)
})
return () => {
setCourseId("");
};
});
return (
<GridContainer>
</GridContainer>
);
};
export default AdminCourse;
i think problem is there with your NavbarContext.js.
you are not exporting NavContext also.
you are defining provider, consumer but you are not using them either.
here's how you can solve your problem.
first create context and it's provider in a file as following.
NavContext.js
import React, { useState } from "react";
const NavContext = React.createContext();
const NavProvider = props => {
const [name, setName] = useState("");
let hookObject = {
name: name,
changeName: setName
};
return (
<NavContext.Provider value={hookObject}>
{props.children}
</NavContext.Provider>
);
};
export { NavProvider, NavContext };
in above code first i am creating context with empty value.
the i am creating NavProvider which actually contains value name as a state hook inside it.hookObject exposes state as per your naming conventions in code.
now i for testing purpose i defined two consumers.
one is where we update name in useEffect, that is ,
ConsumerThatUpdates.js
import React, { useContext, useEffect } from "react";
import { NavContext } from "./NavContext";
const ConsumerThatUpdates = () => {
const { changeName } = useContext(NavContext);
useEffect(() => {
changeName("NEW NAME");
}, [changeName]);
return <div>i update on my useeffect</div>;
};
export default ConsumerThatUpdates;
you can update useEffect as per your needs.
another is where we use the name,
ConsumerThatDisplays.js
import React, { useContext } from "react";
import { NavContext } from "./NavContext";
const ConsumerThatDisplays = () => {
const { name } = useContext(NavContext);
return <div>{name}</div>;
};
export default ConsumerThatDisplays;
and finally my App.js looks like this,
App.js
import React from "react";
import "./styles.css";
import { NavProvider } from "./NavContext";
import ConsumerThatDisplays from "./ConsumerThatDisplays";
import ConsumerThatUpdates from "./ConsumerThatUpdates";
export default function App() {
return (
<div className="App">
<NavProvider>
<ConsumerThatDisplays />
<ConsumerThatUpdates />
</NavProvider>
</div>
);
}
hope this helps!!
if you want to know more about how to use context effectively, i recooHow to use React Context effectively