我试图使用反应钩子来解决一个简单的问题
const [personState,setPersonState] = useState({ DefinedObject });
具有以下依赖关系。
"dependencies": {
"react": "^16.8.6",
"react-dom": "^16.8.6",
"react-scripts": "3.0.0"
}
但我仍然得到以下错误:
/ src / App.js
第7行:
React钩子useState在函数中被调用
“app”既不是React函数组件，也不是自定义React
钩子函数react-hooks/rules-of-hooks
39行:
'state'没有定义
no-undef
搜索关键字以了解关于每个错误的更多信息。
组件代码如下:
import React, {useState} from 'react';
import './App.css';
import Person from './Person/Person';
const app = props => {
const [personState, setPersonSate] = useState({ person:[ {name:'bishnu',age:'32'}, {name:'rasmi',age:'27'}, {name:'fretbox',age:'4'} ], });
return (
<div className="App">
<h2>This is react</h2>
<Person name={personState.person[1].name} age="27"></Person>
<Person name={personState.person[2].name} age="4"></Person>
</div> );
};
export default app;
人组件
import React from 'react';
const person = props => {
return(
<div>
<h3>i am {props.name}</h3>
<p>i am {props.age} years old</p>
<p>{props.children}</p>
</div>
)
};
export default person;
使用大写字母定义功能组件名称/ React挂钩自定义组件。const 'app'应该是const 'app'。
App.js
import React, { useState } from 'react';
import { Component } from 'react';
import logo from './logo.svg';
import './App.css';
import Person from './Person/Person';
const App = props => {
const [personState, setPersonState] = useState({
persons : [
{name: 'a', age: '1'},
{name: 'b', age: '2'},
{name: 'c', age: '3'}
]
});
return (
<div>
<Person name = {personState.persons[0].name} age={personState.persons[0].age}> First </Person>
<Person name = {personState.persons[1].name} age={personState.persons[1].age}> Second </Person>
<Person name = {personState.persons[2].name} age={personState.persons[2].age}> Third </Person>
);
};
export default App;
Person.js
import React from 'react';
const person = (props) => {
return (
<div>
<p> My name is {props.name} and my age is {props.age}</p>
<p> My name is {props.name} and my age is {props.age} and {props.children}</p>
<p>{props.children}</p>
</div>
)
};
[反应物][useState][反应物]
不要使用箭头函数创建功能组件。
按照下面的例子做:
function MyComponent(props) {
const [states, setStates] = React.useState({ value: '' });
return (
<input
type="text"
value={states.value}
onChange={(event) => setStates({ value: event.target.value })}
/>
);
}
Or
//IMPORTANT: Repeat the function name
const MyComponent = function MyComponent(props) {
const [states, setStates] = React.useState({ value: '' });
return (
<input
type="text"
value={states.value}
onChange={(event) => setStates({ value: event.target.value })}
/>
);
};
如果你有“ref”的问题(可能在循环中)，解决方案是使用forwardRef():
// IMPORTANT: Repeat the function name
// Add the "ref" argument to the function, in case you need to use it.
const MyComponent = React.forwardRef( function MyComponent(props, ref) {
const [states, setStates] = React.useState({ value: '' });
return (
<input
type="text"
value={states.value}
onChange={(event) => setStates({ value: event.target.value })}
/>
);
});
