Forgot Content Type JSON Header

A Visual Studio Code extension that helps you avoid a common mistake when using the fetch API: forgetting to set the "Content-Type": "application/json" header when sending JSON data in the request body.

Features

• Automatic detection: Scans your JavaScript/TypeScript files for fetch calls that use body: JSON.stringify(...) but are missing the correct Content-Type header.
• Real-time feedback: Shows a yellow squiggly line under the problematic JSON.stringify call and a warning message.
• Native integration: Uses VS Code's Problems panel and diagnostics system for seamless feedback.

Example

// ❌ This will show a warning
fetch("/api/data", {
  method: "POST",
  body: JSON.stringify(data), // <- squiggly line here
});

// ✅ This won't show a warning
fetch("/api/data", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
  },
  body: JSON.stringify(data),
});

How It Works

• Activates for JavaScript, TypeScript, and their React variants.
• Monitors your code as you type or open files.
• Detects fetch calls with a JSON body but missing the correct Content-Type header.
• Warns you with a squiggly line and a message: Using JSON.stringify() without "Content-Type": "application/json" header.

Supported Languages

• JavaScript (.js)
• TypeScript (.ts)
• JavaScript React (.jsx)
• TypeScript React (.tsx)

Requirements

• Visual Studio Code v1.74.0 or newer

Installation

1. Install the extension from the VS Code Marketplace or your preferred method.
2. Open or edit any supported file.
3. Warnings will appear automatically as you type or open files—no configuration needed.

Known Issues

• Only works for direct fetch calls with object options.
• May not detect all dynamic or indirect usages of fetch.
• Does not support languages other than JavaScript/TypeScript and their React variants.

Release Notes

0.0.1

• Initial release: Detects missing Content-Type: application/json header in fetch calls with JSON bodies.

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Enjoy safer, more reliable API calls!