useState() hook not updating the value on change

Question

Little context, I am trying to create a form for for getting User Signup.

I first wrote code as following .

import { useState } from 'react';


const SignupComponent = () => {
const [formData, setFormData] = useState({
    name: '',
    email: '',
    password: '',
    error: '',
    loading: false,
    message: '',
    showForm: true
})

const { name, email, password, error, loading, showForm } = formData;

const onChange = e => {
    setFormData({ ...formData, error: false, [e.target.name]: e.target.value })
    console.log(name)

}
const handleSubmit = async e => {
    e.preventDefault();
    console.table({ name, email, password, error, loading, showForm })
}


const signupForm = () => {
    return (
        <form onSubmit={handleSubmit}>
            <div className="form-group">
                <input type="text" className="form-control" placeholder="Enter Your Name" values={name} onChange={e => onChange(e)} />
            </div>

            <div className="form-group">
                <input values={email} onChange={e => onChange(e)} type="email" className="form-control" placeholder="Enter Your Email" />
            </div>

            <div className="form-group">
                <input values={password} onChange={e => onChange(e)} type="password" className="form-control" placeholder="Enter Your Password" />
            </div>

            <div>
                <button className="btn btn-primary">Signup</button>
            </div>
        </form>
    );

};
return <React.Fragment>{signupForm()}</React.Fragment>};
export default SignupComponent;

I noticed that in this code snippet, the state in setFormData is not getting updated, console logging name or any other value returns a empty string.

result for the above code

But after tweaking the code as such

import { useState } from 'react';


const SignupComponent = () => {
const [formData, setFormData] = useState({
    name: '',
    email: '',
    password: '',
    error: '',
    loading: false,
    message: '',
    showForm: true
})

const { name, email, password, error, loading, showForm } = formData;

const handleChange = value => (e) => {
    setFormData({ ...formData, error: false, [value]: e.target.value })
    console.log(name)

}
const handleSubmit = async e => {
    e.preventDefault();
    console.table({ name, email, password, error, loading, showForm })
}


const signupForm = () => {
    return (
        <form onSubmit={handleSubmit}>
            <div className="form-group">
                <input type="text" className="form-control" placeholder="Enter Your Name" values={name} onChange={handleChange('name')} />
            </div>

            <div className="form-group">
                <input values={email} onChange={handleChange('email')} type="email" className="form-control" placeholder="Enter Your Email" />
            </div>

            <div className="form-group">
                <input values={password} onChange={handleChange('password')} type="password" className="form-control" placeholder="Enter Your Password" />
            </div>

            <div>
                <button className="btn btn-primary">Signup</button>
            </div>
        </form>
    );

};
return <React.Fragment>{signupForm()}</React.Fragment> };
export default SignupComponent;

Makes the code work and result is as desired. As in this image. 2nd way

Why is this behaving like this. Why is the first way not working.

Answer 1

see docs, https://reactjs.org/docs/thinking-in-react.html

React’s one-way data flow (also called one-way binding) keeps everything modular and fast.

---

Important thing to solve your question.

1. The Functional Component(FC) state is changed, UI is re-rendered.
2. But, your signupForm render function is declared in FC.
3. So, It is re-delcared as a new, when SignupComponent state is changed.

First. change signupForm render function to FC component.

Second, Pass props to component. Thrid, re-used them.

import React from 'react'; // React is required to render JSX

const FormInput = ({
  type,
  placeholder,
  value,
  onChange,
}) => (
  <div className="form-group">
    <input type={type} className="form-control" placeholder={placeholder} value={value} onChange={onChange} />
  </div>
);

const SignupComponent = () => {
  const [formData, setFormData] = React.useState({
    name: '',
    email: '',
    password: '',
    error: false,
    loading: false,
    message: '',
    showForm: true,
  });

  const {
    name, email, password, error, loading, showForm,
  } = formData;

  const handleChange = (value) => (e) => {
    setFormData({
      ...formData,
      error: false,
      [value]: e.target.value,
    });
    console.log(name);
  };

  const handleSubmit = async (e) => {
    e.preventDefault();
    console.table({
      name, email, password, error, loading, showForm,
    });
  };

  return (
    <form onSubmit={handleSubmit}>
      <FormInput type="text" value={name} placeholder="Enter Your Name" onChange={handleChange('name')} />
      <div>
        <button type="submit" className="btn btn-primary">Signup</button>
      </div>
    </form>
  );
};

export default SignupComponent;

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>

Answer 2

You forgot the name attribute in your inputs, and the value attribute without s

<input name="email" value={email} onChange={onChange} ... />

then

const onChange = e => {
    // The event will get passed as an argument even if you don't bind it in onChange={onChange}.
    console.log(e.target.name, e.target.value)
    setFormData({ ...formData, error: false, [e.target.name]: e.target.value })
}

The event will get passed as an argument.

It works for the second cause you're passing the name as an argument