Code Runner

Execute code snippets safely with output capture and timeout protection.

Quick Start

Run JavaScript

bash

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

Run from File

bash

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

REPL Mode

bash

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

Scripts

run.js

Execute code snippets in various languages.

Usage:

bash

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:

bash

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:

bash

node repl.js --lang <language>

Commands:

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

benchmark.js

Benchmark code execution time.

Usage:

bash

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

Options:

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

Supported Languages

Language	Aliases	Runtime
JavaScript	js, javascript, node	Node.js
TypeScript	ts, typescript	ts-node / tsx
Python	py, python, python3	python3
Shell	sh, shell, bash	/bin/bash

Examples

JavaScript

bash

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

bash

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

Shell Script

bash

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

With Input

bash

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

With Arguments

bash

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

Benchmark

bash

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

Output Format

run.js

json

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

benchmark.js

json

{
  "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

json

{
  "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

•Set timeouts for long-running code
•Capture output for debugging
•Use explicit language flags
•Validate input before execution
•Handle errors gracefully