How to use the netlify-identity-widget.init function in netlify-identity-widget

constructor(props) {
    super(props);
    // Initialize NetlifyIdentity
    typeof window !== 'undefined' && netlifyIdentity.init();
  }
  render() {

import netlifyIdentity from 'netlify-identity-widget'

// check for netlifyIdentity, redirect to admin if user is logging in
netlifyIdentity.on('init', user => {
  if (!user) {
    netlifyIdentity.on('login', () => {
      document.location.href = '/admin/'
    })
  }
})

if (window.localStorage) {
  netlifyIdentity.init()
}

import React from "react";
import ReactDOM from "react-dom";
import "./index.css";
import Routes from "./Routes";
//node modules
import registerServiceWorker from "./registerServiceWorker";
import { unregister } from "./registerServiceWorker";
import { BrowserRouter as Router } from "react-router-dom";
import netlifyIdentity from "netlify-identity-widget";
netlifyIdentity.init();
ReactDOM.render(
  
    
  ,

  document.getElementById("root")
);

// registerServiceWorker();
unregister();

import netlifyIdentity from 'netlify-identity-widget'

// check for netlifyIdentity, redirect to admin if user is logging in
netlifyIdentity.on('init', user => {
  if (!user) {
    netlifyIdentity.on('login', () => {
      document.location.href = '/admin/'
    })
  }
})

if (window.localStorage) {
  netlifyIdentity.init()
  window.netlifyIdentity = netlifyIdentity
}

import React from 'react';
import netlifyIdentity from 'netlify-identity-widget';

netlifyIdentity.init({
  // TODO: figure out why this is not working
  namePlaceholder: 'Username',
});

export const CurrentUserContext = React.createContext({});

class CurrentUserContextProvider extends React.Component {
  state = {
    user: netlifyIdentity.currentUser(),
  };

  authenticate = ({ showSignup = false, onSuccess }) => {
    netlifyIdentity.open(showSignup && 'signup');
    netlifyIdentity.on('login', user => {
      this.setState({ user });
      onSuccess && onSuccess(user);

const addLoginListener = () =>
  netlifyIdentityWidget.on(`login`, () => {
    document.location.href = `${__PATH_PREFIX__}/${CMS_PUBLIC_PATH}/`
  })

netlifyIdentityWidget.on(`init`, user => {
  if (!user) {
    addLoginListener()
  } else {
    netlifyIdentityWidget.on(`logout`, () => {
      addLoginListener()
    })
  }
})

netlifyIdentityWidget.init()

useEffect(() => {
    netlifyIdentity.on("init", handleLogin);
    netlifyIdentity.on("login", handleLogin);
    netlifyIdentity.on("logout", handleLogout);
    netlifyIdentity.init();
  }, []);

componentDidMount() {
    netlifyIdentity.init()
  }