自建PeerJS服务器遇TypeError：无法读取undefined的key属性求助

Hey there, let's tackle this error you're hitting with your PeerJS server on Heroku. The TypeError: Cannot read property 'key' of undefined at config.peerjs.key makes it clear that when your code tries to access the key property, the config.peerjs object itself isn't properly initialized—it's undefined. Let's walk through the most likely causes and fixes:

1. Verify your Config.js export structure #

First, double-check that your Config.js is exporting a configuration object that includes a top-level peerjs property. It should look something like this:

// Example Config.js
module.exports = {
  peerjs: {
    key: 'your-peerjs-api-key',
    // Add other PeerJS configs here (port, path, etc.)
  },
  // Other server configuration properties go here
};

If your export doesn't have this peerjs top-level key, or if you're using an unusual export pattern, config.peerjs will be undefined when you import it elsewhere.

2. Confirm correct import of Config.js in routes.js #

Next, make sure you're importing the config correctly in routes.js, with the right file path and matching import/export style:

• If you used module.exports = {...} (default export) in Config.js, your import should be:

  // Ensure the path matches where Config.js lives relative to routes.js
  const config = require('./Config');
  

• If you used a named export like exports.appConfig = {...}, your import needs to match:

  const { appConfig: config } = require('./Config');
  

A wrong file path (e.g., using ../Config instead of ./Config if they're in the same folder) will also result in an unexpected config object, leading to this error.

3. Check Heroku environment variable setup (if using env vars) #

If you're using Heroku environment variables to store your PeerJS key (instead of hardcoding it), make sure the variable is properly set in your Heroku app:

1. Log into your Heroku dashboard, navigate to your app, and go to Settings > Config Vars
2. Add a variable like PEERJS_KEY with your actual key value
3. Update your Config.js to pull from this env var (with a fallback for local testing):

   module.exports = {
     peerjs: {
       key: process.env.PEERJS_KEY || 'local-test-key',
     },
   };
   

If the env var is missing and you don't have a fallback, this could cause issues—but since your error is about config.peerjs being undefined, this is more of a secondary check.

4. Test locally first to isolate the issue #

Run your server locally and see if you get the same error. If it works locally but breaks on Heroku, the problem is likely with your Heroku deployment:

• Confirm that your Config.js is being pushed to Heroku (check your .gitignore to make sure it's not excluded)
• Use the Heroku CLI to check logs for more context: heroku logs --tail—this might reveal other errors that are preventing your config from loading correctly.

5. Debug the config object directly #

Add a quick debug log right before line 41 in routes.js to see what your config object actually contains:

// Add this above the line throwing the error
console.log('Loaded config object:', config);
console.log('config.peerjs value:', config.peerjs);

Run locally to see the output in your terminal, or check Heroku logs for these messages. This will tell you exactly if config.peerjs exists, and what's in the config object overall.

内容的提问来源于stack exchange，提问作者Kumar Yash