DennyScott

npm install - save-dev @babel/core @babel/cli @babel/plugin-proposal-optional-chaining

DennyScott

const personOne = {
  firstName: "Denny",
  lastName: "Scott",
  contact: {
    phoneNumber: 555–555–5555,
    twitter: "@gitinbit"
  }
}

function getUserForPhoneDirectory(person) {

DennyScott

npx babel - plugins @babel/plugin-proposal-optional-chaining index.js

DennyScott

function getUserForPhoneDirectory(person) {
  var _person$contact;
  const firstName = person === null || person === void 0 ? void 0 : person.firstName;
  const lastName = person === null || person === void 0 ? void 0 : person.lastName;
  const phoneNumber = person === null || person === void 0 ? void 0 : (_person$contact = person.contact) === null || _person$contact === void 0 ? void 0 : _person$contact.phoneNumber;
  if (firstName && lastName && phoneNumber) {
    return `${firstName} ${lastName} - ${phoneNumber}`;
  }
}

DennyScott

{
 "plugins": [ 
   "@babel/plugin-proposal-optional-chaining"
 ]
}

DennyScott

import styled from 'styled-components';

const Card = styled.div`
  box-sizing: border-box;
  max-width: 410px;
  margin: 0 auto;
  padding: 0 2rem;
  display: flex;
  flex-direction: column;
  align-items: center;

DennyScott

import React, { useState } from "react"
...
function App(props) {
  const existingTokens = JSON.parse(localStorage.getItem("tokens"));
  const [authTokens, setAuthTokens] = useState(existingTokens);
  
  const setTokens = (data) => {
    localStorage.setItem("tokens", JSON.stringify(data));
    setAuthTokens(data);
  }

DennyScott

'no-restricted-syntax': [
  'error',
  {
    selector: "CallExpression[callee.name='require']",
    message: 'Require is no longer allowed, please use an import statement'
  }
]

DennyScott

import React, { useState } from 'react'; 

function Header(props) { 
  const [title, setTitle] = useState('Title'); 
}

DennyScott

import React, { useState } from “react”;

export default function App() {
  const [counter, setCounter] = useState(1);

  const onClick = () => {
    setCounter(counter + 1);
    console.log(counter);
  };