index.js:1 Uncaught SyntaxError: Unexpected token <

Question

I'm trying to run our production version of our web app which uses the minified (production) version of React on our IIS server. We can currently run the developer version, but when attempting to run the build version, we keep getting the following error

`index.js:1 Uncaught SyntaxError: Unexpected token <`

I thought it may of been to the minified code in the build folder, so I made a basic index.js with just a alert inside, and it's still failing. I checked the file path, and it seems to be write, and the index.html file seems to be in order as well. We are using the boiler from reactboilerplate.com and running the npm run build command

Dev Console printout:

index.html:

    <!DOCTYPE html>
<html lang="en">

<head>
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width,initial-scale=1">
 <link rel="manifest" href="manifest.json">
 <meta name="mobile-web-app-capable" content="yes">
 <title>Timeclock</title>
</head>

<body>
 <noscript>If you're seeing this message, that means
  <strong>JavaScript has been disabled on your browser</strong>, please <strong>enable JS</strong> to make this app work.</noscript>
 <div id="app"></div>
 <script type="text/javascript" src="index.js"></script>
</body>

</html>

Are you using any JSX in index.js? Have you tried to open index.js directly in the browser and check the output? — Mike Cluck
– Mike Cluck, Commented Jun 21, 2017 at 20:02
no jsx, the index.js file is just a alert function at the moment to just troubleshoot. The output of the index.js file in the browser is valid — Justin E. Samuels
– Justin E. Samuels, Commented Jun 21, 2017 at 20:03
Try opening your console and going to the Sources tab (assuming Chrome). Find index.js in there and see what the browser claims is in it. It might be as simple as a caching issue. — Mike Cluck
– Mike Cluck, Commented Jun 21, 2017 at 20:04
the code you've provided isn't all that relevant to the problem. — user400654
– user400654, Commented Jun 21, 2017 at 20:48

mujib shaikh · Accepted Answer · 2022-07-24 13:26:13Z

2

While linking to index.js file you just need to add the type as "text/JSX" And the error disappears.

<script src="../src/index.js" type="text/JSX"></script>

edited Jul 24, 2022 at 13:26

answered Jul 24, 2022 at 13:25

mujib shaikh

447 bronze badges

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Comments

Sean · Accepted Answer · 2017-06-21 20:46:23Z

1

Inspect your page and verify that when you fetch the index.js file that you're actually getting it. My guess is that when you fetch index.js you'll actually get the index.html, and therefore when your browser attempts to execute a copy of your index.html file as a script, it immediately errors as < is not a valid initial character for a piece of javascript. This is a common misconfiguration people bump into when configuring html push state, so your webserver may not be properly configured to serve index.js properly; make sure you have the following set in your iisconfig.xml file:

<configuration>
    <system.webServer>
        <rewrite>
          <rules>
            <rule name="Main Rule" stopProcessing="true">
                    <match url=".*" />
                    <conditions logicalGrouping="MatchAll">
                        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
                        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
                    </conditions>
                    <action type="Rewrite" url="/" />
                </rule>
            </rules>
        </rewrite>
    </system.webServer>
</configuration>

edited Jun 21, 2017 at 20:46

answered Jun 21, 2017 at 20:06

Sean

517 bronze badges

2 Comments

Mike Cluck Over a year ago

So how does one go about fixing this?

Mike Cluck Over a year ago

Please edit your answer to include the relevant information rather than writing a comment.

Dharman · Accepted Answer · 2021-09-16 23:42:30Z

0

After you set up an index.js and linked with the HTML file, then you should delete the in index.js and run your code directly. the error will disappear! It is that simple, but tricky at the start.

edited Sep 16, 2021 at 23:42

Dharman♦

34k27 gold badges106 silver badges158 bronze badges

answered Sep 16, 2021 at 23:36

Pablo dev

11 bronze badge

Comments

Osama Riar · Accepted Answer · 2022-12-13 02:26:23Z

0

I was getting the same error which was being caused because i was using express.static('public') but that was not the main file there. My 'Public' folder was inside another folder called 'Develop" which was messing the paths up. Pulled everything outside Develop and the problem got solved. Hope this helps

answered Dec 13, 2022 at 2:26

Osama Riar

1

Comments

Sanjay ch · Accepted Answer · 2023-06-11 16:39:02Z

0

While linking to the index.js file you just need to add the type as "text/babel".

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

Also, make sure to add Babel cdn.

<script src="https://unpkg.com/@babel/standalone/babel.min.js"></script>

answered Jun 11, 2023 at 16:39

Sanjay ch

11 bronze badge

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