RaysBookClub/src/pages/Signup.js

import Form from 'react-bootstrap/Form';
import Container from 'react-bootstrap/Container';
import Row from 'react-bootstrap/Row';
import Col from 'react-bootstrap/Col';
import Button from "react-bootstrap/Button"
import {useState, useEffect} from 'react';

export function Signup ( props ) {
   const[username,setUsername] = useState('')
    const[validusername,setValidusername] = useState(false)
   const[useremail,setUseremail] = useState('')
   const[validemail,setValidemail] = useState(false)
    const[password,setUserpassword] = useState('')
    const[validpassword,setValidpassword] = useState(false)
    const submitHandler = (evt) => {
        evt.preventDefault()
    }

    useEffect( () => {
        if(username.length >= 4) {
            setValidusername(true)
        }
        else {
            setValidusername(false)
        }
     }, [username] )

     useEffect( () => {
        if(useremail.indexOf('@') > 0 ) {
            setValidemail(true)
        }
        else {
            setValidemail(false)
        }
     }, [useremail] )

     useEffect( () => {
        if( setUserpassword.length >= 8 ) {
            setValidpassword(true)
        }
        else{
            setValidpassword(false)
        }
    }, [setUserpassword] )

    return (
       
       <Container>
        <Row>
            <Col md={{span: 4, offset:4}}>
           <Form>
                <Form.Group>
                    <Form.Label>Username</Form.Label>
                    <Form.Control
                    type="text"
                    name="username"
                    placeholder='username'
                    onChange={ (evt) => setUsername(evt.target.value) }
                    />
                    </Form.Group>
                    <Form.Group>    
                    <Form.Label>Email</Form.Label>
                    <Form.Control
                    type="email"
                    name="email"
                    placeholder="you@example.com"
                    onChange={ (evt) => setUseremail(evt.target.value) }
                    />
                    </Form.Group>
                    <Form.Group>
                    <Form.Label>Password</Form.Label>
                    <Form.Control
                    type="password"
                    name="password"
                    placeholder='password'
                    onChange={ (evt) => setUserpassword(evt.target.value) }
                    />
                    </Form.Group>
                    <Button
                    variant="primary"
                    className="mt-3 w-100"
                    type="submit">Sign up
                    disabled={ !(validemail && validpassword && validusername) ? false : true }
                    </Button>
                </Form>
                </Col>
                </Row>
       </Container>
    )
}