Node.js / TypeScript

Debugger: js-debug (Microsoft, built into VS Code) Status: Stable Node.js version: 18+

Prerequisites

No installation required. The adapter downloads js-debug automatically on first use and caches it at ~/.krometrail/adapters/js-debug/.

Verify: node --version (must be 18+)

Quick Start

# Debug a Node.js script
krometrail launch "node index.js" --break index.js:42

# Debug TypeScript (ts-node)
krometrail launch "npx ts-node src/app.ts" --break src/app.ts:30

# Debug jest tests
krometrail launch "npx jest tests/order.test.js --no-coverage" \
	--break src/order.js:147

# Debug mocha tests
krometrail launch "npx mocha tests/**/*.test.js" --break src/api.js:83

TypeScript

Source maps are enabled automatically. Set breakpoints against the TypeScript source files, not the compiled JavaScript:

krometrail break "src/order.ts:147 when discount < 0"

The adapter sets outFiles to map compiled output back to source locations. Ensure your tsconfig.json has "sourceMap": true.

Framework Auto-detection

jest and mocha are auto-detected from the launch command. The adapter configures --inspect-brk correctly for each test runner and handles the test runner's argument parsing to avoid conflicts with the debugger flags.

Conditional Breakpoints

JavaScript expressions work in conditions:

krometrail break "order.js:147 when discount < 0"
krometrail break "loop.js:25 when i === 99"
krometrail break "api.js:30 when req.method === 'POST'"

Exception Breakpoints

krometrail break --exceptions uncaught
krometrail break --exceptions all       # including caught exceptions

Evaluating Async Expressions

debug_evaluate supports await in the expression if you're stopped in an async context:

krometrail eval "await user.fetchProfile()"

Tips

• The first launch may take a few seconds while js-debug is downloaded and extracted
• ESM (.mjs, type: "module") is supported
• Worker threads appear as separate threads in debug_threads
• For Bun: the Bun adapter exists but is not currently supported (Bun uses WebKit JSC protocol, not V8 CDP). Use Node.js for debugging Bun-targeted code during development.