How do I use react custom hooks to make code reusable

Question

I have two components similar like below:

const Login = props => {
    let loading;
    const dispatch = useDispatch();
    const [notification, setNotification] = React.useState('');
    const [hasNotification, setHasNotification] = React.useState('');
    const [isLoading, setIsLoading] = React.useState(false);
    const {status, message} = useSelector(state => state.LoginReducer);
    const { register, handleSubmit, formState, errors } = useForm({
        mode: "onChange"
    });
    const onSubmit = data => {
        setIsLoading(true);
        dispatch(loginStart(data));
    };
    React.useEffect(() => {
        setIsLoading(false);
        if (status === 422) {
            setNotification(message);
            setHasNotification('ERROR');
            return;
        }
        if (status === 200) {
            setNotification(message);
            setHasNotification('SUCCESS');
        }
    }, [status, message]);
    React.useEffect(() => {
        console.log('componentDidMount');
        return () => {
            setNotification('');
            setHasNotification('');
        };
    }, []);
    return (
        <AuthLayout title={'Login'} header={'Welcome back, Sign in'} hasNotification={hasNotification} notification={notification}>
        </AuthLayout>
    )
}
export default Login;

I also have another component with similar functionality as above

const Signup = props => {
    let loading;
    const dispatch = useDispatch();
    const [notification, setNotification] = React.useState('');
    const [hasNotification, setHasNotification] = React.useState('');
    const [isLoading, setIsLoading] = React.useState(false);
    const {status, message} = useSelector(state => state.SignupReducer);
    const { register, handleSubmit, formState, errors } = useForm({
        mode: "onChange"
    });
    const onSubmit = data => {
        setIsLoading(true);
        dispatch(signupStart(data));
    };
    React.useEffect(() => {
        setIsLoading(false);
        if (status === 422) {
            setNotification(message);
            setHasNotification('ERROR');
            return;
        }
        if (status === 200) {
            setNotification(message);
            setHasNotification('SUCCESS');
        }
    }, [status, message]);
    React.useEffect(() => {
        console.log('componentDidMount');
        return () => {
            setNotification('');
            setHasNotification('');
        };
    }, []);
    return (
        <AuthLayout title={'Signup'} header={'Discover a new way to do amazing work'} hasNotification={hasNotification} notification={notification}>
        </AuthLayout>
    )
}
export default Signup;

I read about custom hooks but just curious how I can move the state and logic to a separate custom hook function since they have similar structure and functionalities.

What will the custom hook look like?

Answer 1

You can declare all your state/hooks logic in a function and export it to your component:

Example: For your login component you can extract your logic to a file, let's call it useLogin.js

useLogin.js:

export default () => {
    const [notification, setNotification] = React.useState('');
    const [hasNotification, setHasNotification] = React.useState('');
    const [isLoading, setIsLoading] = React.useState(false);
    const { register, handleSubmit, formState, errors } = useForm({
        mode: "onChange"
    });
    React.useEffect(() => {
        setIsLoading(false);
        if (status === 422) {
            setNotification(message);
            setHasNotification('ERROR');
            return;
        }
        if (status === 200) {
            setNotification(message);
            setHasNotification('SUCCESS');
        }
    }, [status, message]);
    React.useEffect(() => {
        console.log('componentDidMount');
        return () => {
            setNotification('');
            setHasNotification('');
        };
    }, []);
   return [notification, hasNotification, setIsLoading]; //return all variable and functions that you need in your component
}

And in Login you should import your function and use it

import useLogin from './useLogin'; // first import useLogin function
const Login = props => {
    let loading;
    const dispatch = useDispatch();
    const {status, message} = useSelector(state => state.LoginReducer);
    const [notification, hasNotification, setIsLoading] = useLogin(); // call useLogin and get notification and hasNotification objects
    const onSubmit = data => {
        setIsLoading(true);
        dispatch(loginStart(data));
    };
    return (
        <AuthLayout title={'Login'} header={'Welcome back, Sign in'} hasNotification={hasNotification} notification={notification}>
        </AuthLayout>
    )
}
export default Login;

Same thing to Signup component

import useLogin from './useLogin';
const Signup = props => {
    let loading;
    const dispatch = useDispatch();
    const {status, message} = useSelector(state => state.SignupReducer);
    const [notification, hasNotification, setIsLoading] = useLogin();
    const onSubmit = data => {
        setIsLoading(true);
        dispatch(signupStart(data));
    };
    return (
        <AuthLayout title={'Signup'} header={'Discover a new way to do amazing work'} hasNotification={hasNotification} notification={notification}>
        </AuthLayout>
    )
}
export default Signup;

Hope the idea was clear;

Answer 2

You can create a new component with the same code, the difference is in the title and header from AuthLayout

<AuthLayout title={props.title} header={props.header} hasNotification={hasNotification} notification={notification}></AuthLayout>

Login

const Login = props => {
    return (
        <newComponent title={'Login'} header={'Welcome back, Sign in'} />
    )
}
export default Login;

SignUp

const SignUp = props => {
    return (
        <newComponent title={'SignUp'} header={'Discover a new way to do amazing work'} />
    )
}
export default SignUp;

I called newComponent, the component that you will create