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[]+[])[!+[]+!+[]]+(!![]+[][(![]+[])[+[]]+(![]+[])[!+[]+!+[]]+(![]+[])[+!+[]]+(!![]+[])[+[]]])[+!+[]+ [+[]]]+(!![]+[])[+!+[]]]()[+!+[]+[!+[]+!+[]]])()) You may have heard of both the `MEAN/MERN `_ stacks, and both use Express. Let's try adding Express - it is a Javascript library, after all! Try adding the `Express.js starter code `_ for a basic hello world server as inline javascript: .. code-block:: javascript const express = require('express') const app = express() const port = 3000 app.get('/', (req, res) => { res.send('Hello World!') }) app.listen(port, () => { console.log(`Example app listening at http://localhost:${port}`) }) When inspecting your browser debugger, you should immediately encounter a bug of the form :code:`Uncaught ReferenceError: require is not defined`. Yikes. This Javscript isn't designed for the browser. Finally, let's try making our tiny HTML file a React app. When navigating to the the Create React App `tutorial `_, we are immediately recommended to "use an integrated toolchain for the best user and developer experience." Thankfully, there's a link to add React as a "plain" :code:`

Even after we parse through all the warnings that this isn't suited for production, we see that it "slowly compiles JSX with Babel." There also looks to be HTML within the javascript section of the app. The :code:`