import './App.css';
import io from 'socket.io-client'
import { useEffect, useRef, useState } from 'react'
import React from 'react';
import ReactDOM from "react-dom/client";
const socket = io.connect("http://localhost:3001");
function App() {
const [message, setMessage] = useState("");
const [state, setState] = useState([]);
const [chat, setChat] = useState([]);
const socketRef = useRef();
const sendMessage = () => {
socket.emit("send_message", { message });
};
const renderChat = () => {
return (
chat.map(msg => {
console.log(msg.data)
return (
<h3>{msg.data["message"]}</h3>
)
})
)
}
useEffect(() => {
socketRef.current = io.connect("http://localhost:3001")
socketRef.current.on("receive_message", ({ message }) => {
setChat([ ...chat, { message } ])
})
return () => socketRef.current.disconnect()
},
[ chat ]
)
return (
<div className="App">
<input placeholder="Message..." onChange={(event) => {
setMessage(event.target.value);}}
/>
<button onClick={sendMessage}>Send Message</button>
<h1>Message:</h1>
{renderChat()}
</div>
);
}
export default App;
For some reason the useEffect that needs to store information doesn't work. I have tried a few solutions to store new values in an array useState but I always get this error:
When I do it like this:
useEffect(() => {
socket.on("receive_message", message => {
setChat([...chat, {message}]);
});
}, [socket])
it works but it doesn't save the information (it always has only 1 value which is the latest input text).
You can do it like in the second approach you mentioned, using the previous State:
useEffect(() => {
socket.on("receive_message", message => {
setChat(prevState => [...prevState, {message}]);
});
}, [socket])
You try
useEffect(() => {
socket.on("receive_message", ({ message }) => {
if(!!message){
setChat(prev => [ ...prev, { message } ])
}
})
return () => socket.disconnect()
},[ socket ])
Related
Can I perform client-side data fetching inside a component that's being rendered on a server-side rendered page? I have a page located at pages/solution/[solutionId]/index.js, which is server-side rendered, and it contains three components that should be performing client-side fetching. However, I am not getting any data, and it is returning null.
index.js
const Solution = ({ solution }) => {
const [isOpen, setIsOpen] = useState(false)
const router = useRouter()
const { id } = router.query
const { user } = useAuthContext()
return (
<>
<div className="px-5 row-start-2 row-end-3 col-start-2 col-end-3 mb-4">
// doing client-side fetching
<ShowWebsite
url={solution?.liveWebsiteUrl}
github={solution?.githubUrl}
title={solution?.title}
isPlayground={solution?.isPlayground}
/>
<div className="grid grid-col-1 md:grid-cols-[1fr_160px] items-start gap-x-5 mt-10">
<SolutionComments /> // doing client side fetching
<EmojiSection /> // doing client side fetching
</div>
</div>
</>
)
}
export default Solution
export async function getServerSideProps({ query }) {
const { solutionId } = query
console.log(solutionId)
const solution = await getDocument("solutions", solutionId)
return {
props: {
solution,
},
}
}
SolutionsComment:
import { useState } from "react"
import { useRouter } from "next/router"
import { useCollection } from "../../hooks/useCollection"
import Comment from "./Comment"
import CommentForm from "./CommentForm"
const SolutionComments = () => {
const router = useRouter()
const { id } = router.query
const { documents } = useCollection(`solutions/${id}/comments`)
return (
<div className="mt-10 md:mt-0">
<CommentForm docID={id} />
<div className="mt-10">
{documents &&
documents.map((comment) => (
<Comment
key={comment.id}
comment={comment}
replies={comment.replies}
/>
))}
</div>
</div>
)
}
EmojiSection:
import React from "react"
import { useRouter } from "next/router"
import { useDocument } from "../../hooks/useDocument"
import Emoji from "./Emoji"
const EmojiSection = () => {
const router = useRouter()
const { id: docID } = router.query
const { document: reactions } = useDocument(`solutions/${docID}/reactions`, "emojis")
console.log(reactions)
return (
// JSX CODE
)
}
useCollection:
import { collection, onSnapshot} from "firebase/firestore"
export const useCollection = (c) => {
const [documents, setDocuments] = useState([])
const [isLoading, setIsLoading] = useState(true)
const [error, setError] = useState(null)
useEffect(() => {
let ref = collection(db, c)
const unsubscribe = onSnapshot(ref, (snapshot) => {
const results = []
snapshot.docs.forEach(
(doc) => {
results.push({ ...doc.data(), id: doc.id })
},
(error) => {
console.log(error)
setError("could not fetch the data")
}
)
// update state
setDocuments(results)
setIsLoading(false)
setError(null)
})
return () => unsubscribe()
}, [])
return { documents, error, isLoading }
}
I used this code to show the id of a product.
import { useState } from 'react';
import axios from 'axios';
const BASE_URL = "https://makeup-api.herokuapp.com/api/v1/products";
const useGetProduct = () => {
const [products, setProducts] = useState([]);
const [singleProduct, setSingleProduct] = useState(null);
const getTopProducts = () => {
axios.get(`${BASE_URL}.json`, {
params: {
product_tags: 'Canadian',
},
})
.then(Response => setProducts(Response.data));
};
const getSingleProduct = () => {
axios.get(`${BASE_URL}/1048.jason`)
.then(Response => setSingleProduct(Response.data));
};
return {
products,
getTopProducts,
singleProduct,
getSingleProduct,
}
};
export default useGetProduct;
import React, { useEffect } from "react";
import { useParams } from "react-router-dom";
import useGetProduct from "../hooks/useGetProduct";
const Product = () => {
const { id } = useParams();
const { singleProduct, getSingleProduct } = useGetProduct();
useEffect(() => {
getSingleProduct();
}, []);
return (
<div>
<p>Product: {id}</p>
</div>
);
};
export default Product;
app.js
<Route exact path="/product/:id" element={<Product />} />
But when I change <p>Product: {id}</p> to <p>Product: {singleProduct?.name}</p> the product name does not display. Instead, it just shows Product: without the details about the product on localhost and I am not sure why.
const Product = () => {
const { id } = useParams();
const { singleProduct, getSingleProduct } = useGetProduct();
useEffect(() => {
getSingleProduct();
}, []);
return (
<div>
<p>Product: {singleProduct?.name}</p>
</div>
);
};
export default Product;
I want to show details about a single product via a hook in react js.
const { id } = useParams();
const { singleProduct, getSingleProduct } = useGetProduct();
useEffect(() => {
getSingleProduct();
}, []);
You are not using the id from useParams. Shouldn't you pass it to getSingleProduct, I assume that singleProduct is undefined.
I'm developing a pokedex using pokeAPI through react, but I'm developing a feature where I can favorite pokemons and with that through a context, I can store the names of these pokemons in a global array. I've already managed to test and verify that the pokemon names are going to this "database" array inside the pokeDatabase const in my context, but my goal now is to pass this array to localstorage so that the browser recognizes these favorite pokemons instead of disappearing every time I refresh the page, my solution was to try to create a useEffect inside the context so that every time I refresh my application, this information is saved in localStorage, but without success. What better way to achieve this?
context:
import { createContext } from "react";
const CatchContext = createContext({
pokemons: null,
});
export default CatchContext;
provider
import React, { useEffect } from "react";
import CatchContext from "./Context";
const pokeDatabase = {
database: [],
};
const CatchProvider = ({ children }) => {
useEffect(() => {
const dataStorage = async () => {
await localStorage.setItem('pokemons', JSON.stringify(pokeDatabase.database));
}
dataStorage();
}, [])
return (
<CatchContext.Provider value={{ pokemons: pokeDatabase }}>
{children}
</CatchContext.Provider>
);
}
export default CatchProvider;
pageAddPokemon
import * as C from './styles';
import { useContext, useEffect, useState } from 'react';
import { useApi } from '../../hooks/useApi';
import { useNavigate, useParams } from 'react-router-dom';
import PokeInfo from '../../components/PokeInfo';
import AddCircleOutlineIcon from '#mui/icons-material/AddCircleOutline';
import DoNotDisturbOnIcon from '#mui/icons-material/DoNotDisturbOn';
import CatchContext from '../../context/Context';
const SinglePokemon = () => {
const api = useApi();
const { pokemons } = useContext(CatchContext);
const { name } = useParams();
const navigate = useNavigate();
const handleHompage = () => {
navigate('/');
}
const [loading, setLoading] = useState(false);
const [imgDatabase, setImgDatabase] = useState('');
const [infoPokemon, setInfoPokemon] = useState([]);
const [pokemonTypes, setPokemonTypes] = useState([]);
const [isCatch, setIsCatch] = useState(false);
useEffect(() => {
const singlePokemon = async () => {
const pokemon = await api.getPokemon(name);
setLoading(true);
setImgDatabase(pokemon.sprites);
setInfoPokemon(pokemon);
setPokemonTypes(pokemon.types);
setLoading(false);
console.log(pokemons.database);
}
singlePokemon();
verifyPokemonInDatabase();
}, []);
const verifyPokemonInDatabase = () => {
if (pokemons.database[infoPokemon.name]) {
return setIsCatch(true);
} else {
return setIsCatch(false);
}
}
const handleCatchAdd = async () => {
if (isCatch === false) {
if (!pokemons.database[infoPokemon.name]);
pokemons.database.push(infoPokemon.name);
setIsCatch(true);
}
}
const handleCatchRemove = async () => {
if (isCatch === true) {
if (!pokemons.database[infoPokemon.name]);
pokemons.database.splice(pokemons.database.indexOf(toString(infoPokemon.name)), 1);
setIsCatch(false);
}
}
return (
<C.Container>
<PokeInfo
name={infoPokemon.name}
/>
<C.Card>
<C.Info>
<C.Imgs>
<img src={imgDatabase.front_default} alt="" />
<img src={imgDatabase.back_default} alt="" />
</C.Imgs>
<h2 id='types'>Tipos</h2>
{pokemonTypes.map(type => {
return (
<C.Types>
<h2>{type.type.name}</h2>
</C.Types>
)
})}
{isCatch ? (
<DoNotDisturbOnIcon id='iconCatched' onClick={handleCatchRemove}/>
): <AddCircleOutlineIcon id='icon' onClick={handleCatchAdd}/>}
</C.Info>
</C.Card>
<C.Return>
<button onClick={handleHompage}>Retornar a Pokédex</button>
</C.Return>
</C.Container>
)
}
export default SinglePokemon;
I have the below code
import React, {useState, useEffect, useCallback} from 'react';
import axios from 'axios';
const Users = () => {
const [users, setUsers] = useState([]);
const [nextPageNumber, setNextPageNumber] = useState(1);
const fetchUsers = useCallback(() => {
axios.get(`https://randomuser.me/api?page=${nextPageNumber}`).then(response => {
const updatedUsers = [...users, ...response.data.results];
setUsers(updatedUsers);
setNextPageNumber(response.data.info.page + 1);
}).catch(error => {
console.log(error)
})
}, [nextPageNumber, users])
useEffect(() => {
fetchUsers();
}, [fetchUsers]);
const fetchNextUser = () => {
fetchUsers();
}
if(users.length === 0){
return <div>No Users available</div>
}
return(
<div>
<button onClick={fetchNextUser}>Fetch Next user</button>
{users.map(user => (
<div key={user.id}>
<div>Name: {user.name.title} {user.name.first} {user.name.last}</div>
<div>
<img src={user.picture.large} alt="Not available"/>
</div>
</div>
))}
</div>
)
}
export default Users;
This is calling the api repeatadlly. I have used the fetchUsers dependency in useEffect and useCallback hook due to eslint errors. I just want to call the api on first mount and on click of Fetch Next user button without any eslint error.
Is there any way we can achieve that?
Have a try with the below changes it will not give you the eslint error messages.
import React, {useState, useEffect, useRef, useCallback} from 'react';
import axios from 'axios';
const Users = () => {
const [users, setUsers] = useState([]);
const nextPageRef = useRef(1)
const fetchUsers = useCallback(() => {
axios.get(`https://randomuser.me/api?page=${nextPageRef.current}`).then(response => {
const updatedUsers = [...response.data.results];
setUsers(prevUsers => [...prevUsers, ...updatedUsers]);
nextPageRef.current = response.data.info.page + 1
}).catch(error => {
console.log(error)
})
}, [])
useEffect(() => {
fetchUsers();
}, [fetchUsers]);
You could simply use
useEffect(() => {
fetchUsers();
}, []);
This will call the fetchUsers function only once.
And when button is pressed, again call the fetchUsers() function
I have built this custom react hook :
import { useEffect, useContext, useState } from 'react';
import { ProductContext } from '../contexts';
import axios from 'axios';
export default function useProducts(searchQuery) {
const [products, setProducts] = useContext(ProductContext);
const [isLoading, setIsloading] = useState(true);
useEffect(() => {
axios
.get(`/shoes?q=${searchQuery ? searchQuery : ''}`)
.then((res) => {
setProducts(res.data);
setIsloading(false);
})
.catch((err) => {
console.error(err);
});
}, [searchQuery, setProducts]);
return { products, isLoading };
}
It basically fetches some data based on a query string that i pass in. The query string comes from an input field :
import React, { useState } from 'react';
import { FiSearch } from 'react-icons/fi';
import { useProducts } from '../../hooks';
export default function SearchBar() {
const [query, setQuery] = useState('');
const handleChange = (e) => {
e.preventDefault();
setQuery(e.target.value);
};
useProducts(query);
return (
<div className="search-form">
<FiSearch className="search-form__icon" />
<input
type="text"
className="search-form__input"
placeholder="Search for brands or shoes..."
onChange={handleChange}
/>
</div>
);
}
The problem is it will fetch while the user is typing. I want it to fetch after the user didnt type for 500 miliseconds.
What I tried is :
setTimeout(() => {
useProducts(query);
}, 500);
But this will return an error saying :
src\components\header\SearchBar.js
Line 14:5: React Hook "useProducts" cannot be called inside a callback. React Hooks must be called in a React function component or a custom React Hook function react-hooks/rules-of-hooks
Search for the keywords to learn more about each error.
You can debounce your value with an additional piece of state. Once query is changed, we set off a 500 ms timer that will set the value of debounced. However, if the effect re-runs, we clear that timer and set a new timer.
import React, { useState, useEffect } from 'react';
import { FiSearch } from 'react-icons/fi';
import { useProducts } from '../../hooks';
export default function SearchBar() {
const [query, setQuery] = useState('');
const [debounced, setDebounced] = useState('');
useEffect(() => {
const timeout = setTimeout(() => {
setDebounced(query);
}, 500);
return () => { clearTimeout(timeout) }
}, [query])
const handleChange = (e) => {
e.preventDefault();
setQuery(e.target.value);
};
useProducts(debounced);
return (
<div className="search-form">
<FiSearch className="search-form__icon" />
<input
type="text"
className="search-form__input"
placeholder="Search for brands or shoes..."
onChange={handleChange}
/>
</div>
);
}
I'd change the useProducts hook to accept a debounce time as a parameter, and have it make the axios call only once the debounce time is up:
useProducts(query, 500);
export default function useProducts(searchQuery, debounceTime = 0) {
const [products, setProducts] = useContext(ProductContext);
const [isLoading, setIsloading] = useState(true);
const [timeoutId, setTimeoutId] = useState();
useEffect(() => {
clearTimeout(timeoutId);
setTimeoutId(setTimeout(() => {
axios
.get(`/shoes?q=${searchQuery ? searchQuery : ''}`)
.then((res) => {
setProducts(res.data);
setIsloading(false);
})
.catch((err) => {
console.error(err);
});
}, debounceTime));
}, [searchQuery, setProducts]);
return { products, isLoading };
}