why I can't set the Data in the first Click I Have to input twice to set the data.
Thanks for your help...
export default function App() {
const [title, setTitle] = useState();
const [projectData, setProjectData] = useState([]);
const handleSubmit = (e) => {
e.preventDefault();
setProjectData([...projectData, { projectTitle: title }]);
console.log(projectData);
};
return (
<div className="App">
<input
type="text"
onChange={(e) => {
setTitle(e.target.value);
}}
/>
<button onClick={handleSubmit}>insert</button>
</div>
);
}
Actually it did, but the setState hook runs asynchronously so the console.log after that won't reflect the change. You could use useEffect to watch for the change of projectData instead
import React, { useEffect, useState } from "react";
export default function App() {
const [title, setTitle] = useState();
const [projectData, setProjectData] = useState([]);
useEffect(() => {
console.log(projectData);
}, [projectData]);
const handleSubmit = (e) => {
e.preventDefault();
setProjectData([...projectData, { projectTitle: title }]);
};
return (
<div className="App">
<input
type="text"
onChange={(e) => {
setTitle(e.target.value);
}}
/>
<button onClick={handleSubmit}>insert</button>
</div>
);
}
In React setState actions are asynchronous and are batched for performance gains. This is explained in the documentation of setState.
If you want to log projectData you can use useEffect hook.
const handleSubmit = (e) => {
e.preventDefault();
setProjectData([...projectData, { projectTitle: title }]);
};
// useEffect with ProjectData as dependency
useEffect(() => {
console.log(projectData);
}, [projectData]);
Related
I am trying to create a debounce search and initially when the field is empty the component renders after the provided setTimeout delay. But if I continue to search with the existing keyword it re-renders the List component on each key stroke. How to avoid that?
import { useEffect, useState } from 'react';
import useDebounce from './hooks/useDebounce';
import List from './components/List';
const App: React.FC = () => {
const [todo, setTodo] = useState<string>("");
const [query, setQuery] = useState<string | null>("");
let deBounceSearch = useDebounce(query, 2000);
useEffect(() => {
if (deBounceSearch) {
console.log('Searching...');
} else {
console.log('...');
}
}, [deBounceSearch]);
return (
<div className="App">
<input type="text" placeholder='Search anything' onChange={(e) => setQuery(e.target.value)} />
{deBounceSearch !== '' && (
<List />
)}
</div>
);
}
useDebounce.tsx
const useDebounce = (value: any, delay: number) => {
const [debouncedValue, setDebouncedValue] = useState(value);
useEffect(() => {
const handler = setTimeout(() => { setDebouncedValue(value) }, delay);
return () => {
clearTimeout(handler);
}
}, [value, delay]);
return debouncedValue;
}
export default useDebounce;
You can use useMemo to avoid re-render the List component every time query value changes:
const App: React.FC = () => {
const [todo, setTodo] = useState<string>("");
const [query, setQuery] = useState<string | null>("");
const deBounceSearch = useDebounce(query, 2000);
// ->
const cachedList = React.useMemo(() => <List />, [debouncedValue]);
...
return (
<div className="App">
<input type="text" placeholder='Search anything' onChange={(e) => setQuery(e.target.value)} />
{deBounceSearch !== '' && cachedList}
</div>
);
}
You also can take a look at React.memo
hello man this is not the best to use debounce i suggest u try lodash debounce with useMemo.
but for now the solution for your code is that you forgot to clear the timeout on every time the value change.
here the solution:
import { useEffect, useState, useRef } from "react";
import "./styles.css";
const useDebounce = (value, delay) => {
const [debouncedValue, setDebouncedValue] = useState(value);
const handler = useRef();
useEffect(() => {
if (handler.current) {
clearTimeout(handler.current);
}
handler.current = setTimeout(() => {
setDebouncedValue(value);
}, delay);
return () => {
clearTimeout(handler.current);
};
}, [value, delay]);
return debouncedValue;
};
export default function App() {
const [value, setValue] = useState("");
const debounceSearch = useDebounce(value, 2000);
console.log(debounceSearch);
return (
<div className="App">
<input value={value} onChange={(e) => setValue(e.target.value)} />
<h2>Start editing to see some magic happen!</h2>
</div>
);
}
hope this help .
I'm new to react.
Now trying to make form with react hooks, and I want to render Cloud component only when press submit button. But it rendered every onChange called.
I know that onChange re-rendered cause also useState hook.
But have no idea how to render only when press submit button.
My final goal is when write name and press enter, if value is not contained in api, setShake make shake True and if True, put shake-cloud class in Cloud.js.
REACT IS TOO DIFFICULT :(
Thanks for help tho :)
App.js
import React, { useState, useEffect } from "react";
import "./App.css";
import { FontAwesomeIcon } from "#fortawesome/react-fontawesome";
import { faSearch } from "#fortawesome/free-solid-svg-icons";
import "./search.css";
import PageTitle from "./component/PageTitle";
import Cloud from "./component/Cloud";
import Loading from "./component/Loading";
//https://api.color.pizza/v1/
//data.colors[0].name
const App = () => {
const [isLoading, setIsLoading] = useState(false);
const [colorNames, setColorNames] = useState("");
const [search, setSearch] = useState("");
const [query, setQuery] = useState("");
const [cloudHex, setCloudHex] = useState("ivory");
const [shake, setShake] = useState(false);
useEffect(() => {
getColorLists();
}, []);
const getColorLists = async () => {
const res = await fetch(`https://api.color.pizza/v1/`);
const data = await res.json();
await setColorNames(data);
setIsLoading(true);
};
const isColor = () => {
let makeUpper =
query.search(/\s/) == -1
? query.charAt(0).toUpperCase() + query.slice(1)
: query
.split(" ")
.map((i) => i.charAt(0).toUpperCase() + i.slice(1))
.join(" ");
for (let i = 0; i < colorNames.colors.length; i++) {
if (colorNames.colors[i].name == makeUpper) {
setCloudHex(colorNames.colors[i].hex);
return;
} else if (i == colorNames.colors.length - 1) {
return makeShake();
}
}
};
const updateSearch = (e) => {
setSearch(e.target.value);
};
const getSearch = (e) => {
e.preventDefault();
setQuery(search);
isColor();
};
const makeShake = async () => {
await setShake(true)
await setShake(false)
}
return (
<>
{!isLoading ? (
<Loading />
) : (
<div className="App">
<div className="app-wrap">
<PageTitle />
<div className="search-wrap">
<form onSubmit={getSearch} className="search-form">
<input
className="search-bar"
type="text"
value={search}
onChange={updateSearch}
/>
<button type="submit" className="search-button">
<FontAwesomeIcon
icon={faSearch}
className="search"
/>
</button>
</form>
</div>
<Cloud cloudhex={cloudHex} shake={shake} />
</div>
</div>
)}
</>
);
};
export default App;
Cloud.js
import React, {useEffect} from "react";
import { FontAwesomeIcon } from "#fortawesome/react-fontawesome";
import { faCloud } from "#fortawesome/free-solid-svg-icons";
import './cloud.css';
const Cloud = ({cloudhex, shake}) => {
useEffect(() => {
}, [])
console.log(shake)
return (
<div className={`cloud-wrap ${ shake ? "shake-cloud":''}`}>
<span className="cloudhexname">{cloudhex}</span>
<FontAwesomeIcon icon={faCloud} className="cloud" style={{color:`${cloudhex}`}} />
</div>
);
};
export default Cloud;
A good approach in this case is to use useRef() Hook to store our search field value, instead of using useState(). Because useRef() Hook does not force a re-render while useState() does. This approach is known as un-controlled way to use input field.
You basically need to make few modifications in your code which are as follows:
const search = useRef("");
Then remove onChange={updateSearch} and value={search} from input and use a property ref={search}. So that your input looks like below:
<input
className="search-bar"
type="text"
ref={search}
/>
Then in the submit handler, you can get the value of the input field using search.current.value. So your getSearch() would look like
const getSearch = (e) => {
e.preventDefault();
setClicked(true);
setQuery(search.current.value);
isColor();
};
Assuming user has typed an input. If not then you can set a validation before using setQuery() in the getSearch() form submit handler.
if(search.current.value){
setQuery();
}
Note: If you have any other controlled inputs in your project, you can change then to un-controlled inputs using refs and this way re-renders would not happen in your code.
Do it like that
If you want to render cloud component after form submit then put one flag and toggle that, here I take clicked state
import React, { useState, useEffect } from "react";
import "./App.css";
import { FontAwesomeIcon } from "#fortawesome/react-fontawesome";
import { faSearch } from "#fortawesome/free-solid-svg-icons";
import "./search.css";
import PageTitle from "./component/PageTitle";
import Cloud from "./component/Cloud";
import Loading from "./component/Loading";
//https://api.color.pizza/v1/
//data.colors[0].name
const App = () => {
const [isLoading, setIsLoading] = useState(false);
const [colorNames, setColorNames] = useState("");
const [search, setSearch] = useState("");
const [query, setQuery] = useState("");
const [cloudHex, setCloudHex] = useState("ivory");
const [shake, setShake] = useState(false);
const [clicked, setClicked] = useState(false);
useEffect(() => {
getColorLists();
}, []);
const getColorLists = async () => {
const res = await fetch(`https://api.color.pizza/v1/`);
const data = await res.json();
await setColorNames(data);
setIsLoading(true);
};
const isColor = () => {
let makeUpper =
query.search(/\s/) == -1
? query.charAt(0).toUpperCase() + query.slice(1)
: query
.split(" ")
.map((i) => i.charAt(0).toUpperCase() + i.slice(1))
.join(" ");
for (let i = 0; i < colorNames.colors.length; i++) {
if (colorNames.colors[i].name == makeUpper) {
setCloudHex(colorNames.colors[i].hex);
return;
} else if (i == colorNames.colors.length - 1) {
return makeShake();
}
}
};
const updateSearch = (e) => {
setSearch(e.target.value);
};
const getSearch = (e) => {
e.preventDefault();
setClicked(true);
setQuery(search);
isColor();
};
const makeShake = async () => {
await setShake(true)
await setShake(false)
}
return (
<>
{!isLoading ? (
<Loading />
) : (
<div className="App">
<div className="app-wrap">
<PageTitle />
<div className="search-wrap">
<form onSubmit={getSearch} className="search-form">
<input
className="search-bar"
type="text"
value={search}
onChange={updateSearch}
/>
<button type="submit" className="search-button">
<FontAwesomeIcon
icon={faSearch}
className="search"
/>
</button>
</form>
</div>
{clicked && <Cloud cloudhex={cloudHex} shake={shake} />}
</div>
</div>
)}
</>
);
};
export default App;
I have a component Search component with suggestions. I create the suggestions by javascript. I can print all the suggestions, but how I can select the suggest element to put into the placeholder? Thanks for your response.
SEARCH COMPONENT
import React, { useEffect, useState } from "react";
import api from "../../api/index";
import "./index.css";
export default function Search(query) {
const [searchSchool, setSearchShool] = useState("");
const [showSuggestions, setShowSuggestions] = useState(false);
const [allSchools, setAllSchools] = useState([]);
const inputRef = React.useRef(null);
useEffect(() => {
(async () => {
const data = await api.getSchools();
setAllSchools(data);
})();
}, []);
const resultsAllSchools = !searchSchool
? allSchools
: allSchools.filter(school => school.toLowerCase().includes(searchSchool));
const handleOnclick = e => {
e.preventDefault();
const lowerCase = e.target.value.toLowerCase();
setSearchShool(lowerCase);
setShowSuggestions(true);
if (e.target.value === "" || null) {
setShowSuggestions(false);
}
};
return (
<>
<form>
<input
className="select"
type="text"
placeholder="Cerca el teu centre educatiu"
value={searchSchool}
ref={inputRef}
onChange={handleOnclick}
></input>
<button>
</button>
<ul>
{showSuggestions &&
resultsAllSchools.map((item, i) => <li key={i}>{item}</li>)}
</ul>
</form>
</>
);
}
I'm trying to build edit form fields. Here, you have to press a button before you can edit the form field. However, I'm having problems toggling the disabled prop and setting the focus of the element. This is some sample code. The input will only focus after I've clicked the button twice.
export default function App() {
const [isDisabled, setIsDisabled] = useState(true);
const inputEl = useRef(null);
const onBlur = () => {
setIsDisabled(true);
};
const handleEditClick = () => {
setIsDisabled(false);
inputEl.current.focus();
};
return (
<div className="App">
<h1>Focus problem</h1>
<h2>Focus only happens on the scond click!</h2>
<input ref={inputEl} onBlur={onBlur} disabled={isDisabled} />
<button onClick={() => handleEditClick()}>Can edit</button>
</div>
);
}
Here is a code-sandbox
Setting focus on a DOM element is a side-effect, it should be done within useEffect:
import React, { useState, useRef, useEffect } from "react";
import "./styles.css";
export default function App() {
const [isDisabled, setIsDisabled] = useState(true);
const inputEl = useRef(null);
useEffect(() => {
inputEl.current.focus();
}, [isDisabled]);
const onBlur = () => {
setIsDisabled(true);
};
const handleEditClick = () => {
setIsDisabled(false);
};
return (
<div className="App">
<h1>Focus problem</h1>
<h2>Focus only happens on the scond click!</h2>
<input ref={inputEl} onBlur={onBlur} disabled={isDisabled} />
<button onClick={() => handleEditClick()}>Can edit</button>
</div>
);
}
I am trying to convert class component of todo app into functional component. Everything goes well, but when I submit the form, the blank screen appears. I think there is some issue in handleSubmit function. Please help.
import React, {useState} from "react";
export const TodoFunc = (props: Props) => {
const [items, setItems] = useState([])
const [text, setText] = useState('')
const handleChange = (e) => {
setText(e.target.value)
}
const handleSubmit = (e) => {
e.preventDefault()
if (text.length === 0) {
return;
}
const newItems = {text: {text}, id: Date.now()}
setItems(() => (items.concat(newItems)))
setText('')
}
return (
<div>
<h3>TODO</h3>
<TodoList items = {items} />
<form onSubmit={handleSubmit}>
<label htmlFor="new-todo">
What do you want to do?
</label>
<input type="text"
id='new-todo'
onChange={handleChange}
value={text}
/>
<button>
Add #{items.length + 1}
</button>
</form>
</div>
);
};
const TodoList = (props) => {
return (
<ul>
{props.items.map(item => <li key={item.id}>{item.text}</li>)}
</ul>
)
}
Your problem lies in the below line:
const newItems = {text: {text}, id: Date.now()}
Here you are assigning an object to the text key and not just the value of the variable text.
And this is why when you loop over them in your TodoList component you are not able to display any of them.