React.js (Reference Error: React is not defined)

Question

I've attached copies of the code below. Only two files in my project now, app.js and index.html. When I go to google developers' tool and console, the log statement isn't going through. When I type react or react-dom into console I am told Reference Error: React is not defined. This is what a Udemy tutorial has told me to do last updated 5/19 so this should work. I have tried putting import React from "react"; in the top of the files but that doesn't work either. Any suggestions?

//app.js
console.log("App.js is running!)


//index.html
<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8">
  <title>Indecision App</title>
</head>

<body>
  <script src="https://unpkg.com/[email protected]/umd/react.development.js"></script>
  <script src="https://unpkg.com/[email protected]/umd/react-dom.development.js"></script>
  <script src="/scripts/app.js"></script>
</body>

</html>

Does it work if you use any current version of react, i.e. React 16.x? — Drew Reese
– Drew Reese, Commented Sep 26, 2020 at 0:31
Are you typing them in lower case like 'react' and 'react-dom'? If so, try React and ReactDOM (no dash in between) — ultimoTG
– ultimoTG, Commented Sep 26, 2020 at 0:34
@Drew Reese. Whoops, I edited it to RN 16.x which is what I meant to originally post! But nope, that does not solve the error! — Sebastian Caceres
– Sebastian Caceres, Commented Sep 26, 2020 at 0:41
@ultimoTG. I have tried both with uppercase, lowercase, with dash, and without dash, still have the same error! — Sebastian Caceres
– Sebastian Caceres, Commented Sep 26, 2020 at 0:42
Seems CDN link may also need to specify a crossorigin attribute on the scripts. — Drew Reese
– Drew Reese, Commented Sep 26, 2020 at 0:45

Drew Reese · Accepted Answer · 2020-09-26 03:28:13Z

1

Looks like you'll need to also specify the crossorigin attribute on the scripts as per the react CDN-links docs.

<script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>

answered Sep 26, 2020 at 3:28

Drew Reese

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