Code Runner

Execute code snippets safely with output capture and timeout protection.

Quick Start

Run JavaScript

node /path/to/skills/code-runner/scripts/run.js --lang js "console.log('Hello')"

Run from File

node /path/to/skills/code-runner/scripts/run.js --file script.py --lang python

REPL Mode

node /path/to/skills/code-runner/scripts/repl.js --lang js

Scripts

run.js

Execute code snippets in various languages.

Usage:

node run.js <code> --lang <language>
node run.js --file <path> --lang <language>

Options:

• --lang <lang> - Language: js, ts, python, py, shell, bash (required)
• --file <path> - Execute code from file instead of argument
• --timeout <ms> - Execution timeout (default: 30000)
• --stdin <data> - Provide stdin input
• --args <args> - Command-line arguments (comma-separated)
• --env <json> - Environment variables as JSON

eval.js

Quick JavaScript expression evaluation.

Usage:

node eval.js <expression>

Features:

• Direct expression evaluation
• Access to Math, JSON, Date built-ins
• Returns evaluated result

repl.js

Interactive REPL for testing code.

Usage:

node repl.js --lang <language>

Commands:

• .exit - Exit REPL
• .clear - Clear context
• .help - Show help

benchmark.js

Benchmark code execution time.

Usage:

node benchmark.js <code> --lang <language> [OPTIONS]

Options:

• --iterations <n> - Number of runs (default: 100)
• --warmup <n> - Warmup runs (default: 10)

Supported Languages

Examples

JavaScript

node run.js --lang js "
const arr = [1, 2, 3, 4, 5];
const sum = arr.reduce((a, b) => a + b, 0);
console.log('Sum:', sum);
"

Python

node run.js --lang python "
import json
data = {'name': 'test', 'value': 42}
print(json.dumps(data, indent=2))
"

Shell Script

node run.js --lang bash "
for i in 1 2 3; do
  echo \"Number: \$i\"
done
"

With Input

node run.js --lang python --stdin "Hello World" "
import sys
data = sys.stdin.read()
print(f'Received: {data}')
"

With Arguments

node run.js --lang js --args "arg1,arg2" "
console.log('Args:', process.argv.slice(2));
"

Benchmark

node benchmark.js --lang js --iterations 1000 "
const result = Array(100).fill(0).map((_, i) => i * 2);
"

Output Format

run.js

{
  "success": true,
  "language": "javascript",
  "exitCode": 0,
  "stdout": "Hello World\n",
  "stderr": "",
  "duration": 45,
  "timedOut": false
}

benchmark.js

{
  "language": "javascript",
  "iterations": 100,
  "warmupRuns": 10,
  "results": {
    "min": 2.3,
    "max": 15.7,
    "mean": 4.2,
    "median": 3.8,
    "stdDev": 2.1,
    "p95": 8.5,
    "p99": 12.3
  },
  "unit": "ms"
}

Security Notes

• Code runs in a subprocess with timeout protection
• No network isolation (use container for full sandbox)
• File system access is available
• Environment variables can be passed explicitly
• For untrusted code, use containerized execution

Error Handling

{
  "success": false,
  "language": "python",
  "exitCode": 1,
  "stdout": "",
  "stderr": "NameError: name 'undefined_var' is not defined",
  "duration": 120,
  "error": "Process exited with code 1"
}

Best Practices

1. Set timeouts for long-running code
2. Capture output for debugging
3. Use explicit language flags
4. Validate input before execution
5. Handle errors gracefully