React Hook “useState” is called in function “app” which is neither a React function component or a custom React Hook function

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I’m trying to use react hooks for a simple problem

const [personState,setPersonState] = useState({ DefinedObject });

with following dependencies.

"dependencies": {
    "react": "^16.8.6",
    "react-dom": "^16.8.6",
    "react-scripts": "3.0.0"
}

but I’m still getting the following error:

./src/App.js

Line 7:
React Hook “useState” is called in function
“app” which is neither a React function component or a custom React
Hook function react-hooks/rules-of-hooks

Line 39:
‘state’ is not defined
no-undef

Search for the keywords to learn more about each error.

Component code is below:

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;

Person component

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;

35 Answers
35

Try to capitalize ‘app’ like

const App = props => {...}

export default App;

In React, components need to be capitalized, and custom hooks need to start with use.

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