ReactJS: “Uncaught SyntaxError: Unexpected token <”

133
votes

I am trying to get started building a site in ReactJS. However, when I tried to put my JS in a separate file, I started getting this error: "Uncaught SyntaxError: Unexpected token <".

I tried adding /** @jsx React.DOM */ to the top of the JS file, but it didn't fix anything. Below are the HTML and JS files. Any ideas as to what is going wrong?

HTML

<html>
  <head>
    <title>Page</title>
    <script src="http://fb.me/react-0.12.2.js"></script>
    <script src="http://fb.me/JSXTransformer-0.12.2.js"></script>
    <script src="http://code.jquery.com/jquery-1.10.0.min.js"> </script>
    <script src="./lander.js"> </script>
  </head>
  <body>
    <div id="content"></div>
    <script type="text/jsx">
        React.render(
            <Lander />,
            document.getElementById('content')
        );
    </script>
  </body>
</html>

JS

/**
 * @jsx React.DOM
 */
var Lander = React.createClass({
    render: function () {
        var info = "Lorem ipsum dolor sit amet... ";
        return(
            <div>
                <div className="info">{info}</div>
            </div>
        );
    }
});

EDIT: I realized that I need to add type="text/jsx" to the script tag which includes my lander code. However, after adding this and reloading I get this warning

"You are using the in-browser JSX transformer. Be sure to precompile your JSX for production - http://facebook.github.io/react/docs/tooling-integration.html#jsx"

followed by this error:

"XMLHttpRequest cannot load file:///Users/.../lander.js. Cross origin requests are only supported for protocol schemes: http, data, chrome-extension, https, chrome-extension-resource."

it seems like there is something else that I need to do in order to get in browser jsx transform working, but I'm not sure what it is.

EDIT: OOOOH do I need to host it using MAMP or something?

10
javascripthtmlreactjsreact-jsx
How are you including your "JS" file? – Quentin
You need to additionally add the following script code. <script src="unpkg.com/@babel/standalone/babel.min.js"></script> – Steven
2019 update: Adding type="text/babel"to the script tag where I'm importing my JS file and the Babel script that @Steven mentioned in the comment above worked for me. – Syknapse

10 Answers

163
votes

UPDATE -- use this instead:

<script type="text/babel" src="./lander.js"></script>

Add type="text/jsx" as an attribute of the script tag used to include the JavaScript file that must be transformed by JSX Transformer, like that:

<script type="text/jsx" src="./lander.js"></script>

Then you can use MAMP or some other service to host the page on localhost so that all of the inclusions work, as discussed here.

Thanks for all the help everyone!

30
votes

JSTransform is deprecated , please use babel instead.

<script type="text/babel" src="./lander.js"></script>
24
votes

Add type="text/babel" as an attribute of the script tag, like this:

<script type="text/babel" src="./lander.js"></script>
16
votes

Add type="text/babel" to the script that includes the .jsx file and add this: <script src="https://npmcdn.com/[email protected]/browser.min.js"></script>

4
votes

If you have something like

Uncaught SyntaxError: embedded: Unexpected token

You probably missed a comma in a place like this:

  var CommentForm = React.createClass({
  getInitialState: function() {
      return {author: '', text: ''};

  }, // <---- DON'T FORGET THE COMMA

  render: function() {
      return (
      <form className="commentForm">
          <input type="text" placeholder="Nombre" />
          <input type="text" placeholder="Qué opina" />
          <input type="submit" value="Publicar" />
      </form>
      )
  }
  });
4
votes

If you are getting an error like this :

SyntaxError: embedded: Unexpected token (107:9) 105

It could be you are missing a curly bracket

3
votes

The code you have is correct. JSX code needs to be compiled to JS:

http://facebook.github.io/react/jsx-compiler.html

1
votes

Try adding in webpack, it solved the similar issue in my project. Specially the "presets" part.

module: {
    loaders: [
        {
            test: /\.jsx?/,
            include: APP_DIR,
            loader: 'babel',
            query  :{
                presets:['react','es2015']
            }
        },
0
votes

I have the same issue with you and I have change something in my server

you might try this

const root = require("path").join(__dirname, "./build");
app.use(express.static(root));
app.get("*", (req, res) => {
  res.sendFile("index.html", { root });
});
0
votes

In addition to Dee Jee solution, After trying out his solution, My error never went.

I noticed(after two days of head scratch) that the browser has cached the files improperly.

  • My browser wasn't able to load the preview of the cached files and status code from express was 301.
  • In the networks tab of the browser dev tools, I get that those files are server from disk cache.

Solution

Remove the cached files. By clearing the browser history in a span of 1 hour, so that all the cached files get deleted.