Hey there! Let’s work through why your fetch call is failing—this is a super common issue when starting out, so don’t worry, we’ll get it sorted.

1. The #1 Issue: File Protocol Restrictions #

Chrome blocks fetch requests when you’re opening files directly via the file:// protocol (like double-clicking an HTML file to launch it). This is a security measure to prevent local file access risks. Here’s how to fix it:

• Use a local web server: It’s easier than it sounds! If you have Python 3 installed, open your terminal/command prompt, navigate to your project folder (where your JS and info.json files are), and run:

  python -m http.server 8000
  

• Then open Chrome and go to http://localhost:8000 (or http://localhost:8000/your-file.html if your HTML isn’t named index.html). Now your fetch will use the http:// protocol, which allows local file requests.

2. Double-Check File Names & Extensions #

Typos or hidden extensions are sneaky culprits:

• Make sure your file is exactly named info.json—no extra spaces, no typos (like info.JSON on case-sensitive systems, though Chrome is usually forgiving here).
• On Windows: Open File Explorer > View > check "File name extensions" to ensure it’s not info.json.txt.
• On Mac: Finder > Preferences > Advanced > check "Show all filename extensions" to verify the extension.

3. Validate Your JSON Syntax #

A tiny mistake in your info.json (like a missing comma or quote) will break the response.json() step. Here’s how to check:

• Open Chrome DevTools (F12 or Ctrl+Shift+I)
• Go to the Network tab
• Run your fetch code again, then look for info.json in the network request list
• Click on it, then check the Response tab—if your JSON loads correctly, you’ll see the data; if not, you’ll spot the syntax error here.
• Alternatively, paste your JSON content directly into the DevTools console and hit enter—valid JSON will show as an object, invalid will throw a syntax error.

4. Log the Actual Error (Don’t Use Generic Messages!) #

Your current catch block hides useful details. Update your code to log the full error:

fetch('info.json')
  .then(response => response.json())
  .then(obj => console.log(obj))
  .catch(error => {
    console.error('Something went wrong:', error); // Logs the full error object
    console.error('Error details:', error.message); // Logs a human-readable message
  });

This will tell you exactly what’s wrong—like a 404 (file not found), CORS issue, or JSON syntax error.

5. Quick Note for Your Auto-Fill Tool #

Once you get the basic fetch working, if you plan to turn this into a Chrome extension, keep in mind extensions have specific rules for loading local files (you’ll need to declare resources in manifest.json). But let’s get the core fetch working first with the local server method above—then we can tackle extension specifics later if needed.

内容的提问来源于stack exchange，提问作者stephanie