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

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

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

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

code-runner

Code Runner

Quick Start

Run JavaScript

Run from File