Reactjs: "Uncaught SyntaxError: Unexpected token <"

Server setup & React JSX handling

Local hosting & server configuration

Launch your page on a local development server like MAMP for a smoother sail. This nifty trick can bypass pesky cross-origin request woes. Gear up for in-browser JSX transformations by fitting Babel into your rig:

<!-- 🎉 Celebration time: You have just invited Babel to the party-->
<script src="https://npmcdn.com/[email protected]/browser.min.js"></script>
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Proper tagging for scripts with JSX

Scripts laden with JSX need to bear the type="text/babel" tattoo. Otherwise, Babel will turn a blind eye when transforming JSX, culminating in syntax errors:

<!-- 🏷️ 'text/babel': For those times when you forget who you are -->
<script type="text/babel" src="./App.js"></script>
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JavaScript file syntax & structure vigilance

A missing brace or a botched-up syntax within your JavaScript file screams for unexpected tokens. Leveraging linting tools like ESLint can spot and fix these indiscretions before they throw a spanner in your workflow.

Setting up ReactJS sans 'unexpected token' pitfalls

While laying the foundation for your ReactJS project, keep the following pointers close to your chest to steer clear of vexing syntax errors:

Transition from JSX transformer to Babel

Remember, the in-browser JSX transformer has bid adieu. So, extend your hospitality to Babel when it comes to JSX transformations.

Correct type attribute for script tags

Pore over your script tags, ensuring that they all sport the apt type attribute. Any slip-up here can lead your JSX transformation down a rabbit hole.

Use a local server to tackle CORS

Reading local files directly in your browser can summon cross-origin request scowls. Ready a local server like MAMP or Express to don the CORS demonslayer mantle.

Additional troubleshooting quick-fixes

These extra pointers can help you diagnose and fix the 'unexpected token' error in a flash:

Verify script inclusions

Make sure that all script files are indeed JavaScript files and not another HTML page. This slip-up often rears its head when crafting routes or handling server responses.

Detect MIME types

Ensure that your server dishes out JavaScript files with the ideal MIME type, application/javascript. Anything else might baffle the modern browsers.

Browser caching woes

Sometimes, the culprit is just an outdated JavaScript file snug in your browser cache. A refreshing hit on Cmd/Ctrl + Shift + R can dislodge the cache. Alternatively, configure cache-busting techniques on your development server.