AI-Powered Code Review Tool

What is Prompt Engineering?

THE ART OF TALKING TO AI · SYSTEM VS USER MESSAGES

🎯 PROMPT ENGINEERING TIPS

1. Define a persona — "You are a senior JavaScript developer" sets expectations. 2. Structure the output  Asking for specific sections (strengths, improvements, refactored code) ensures consistent responses. 3. Be instructive "Be constructive, kind, and educational" shapes the tone. 4. Use examples Showing the format you want improves results dramatically.

Build the Code Review Tool

OPENAI API · SYSTEM PROMPT · ASYNC/AWAIT

📜 CODE BLOCK 1: Complete AI Code Review Tool (with line-by-line comments)

// ============================================
// AI-POWERED CODE REVIEW TOOL
// ============================================

// STEP 1: Install the OpenAI package first
// $ npm install openai

// STEP 2: Import the OpenAI SDK
// WHY: This gives us access to GPT models via API
const OpenAI = require("openai");

// STEP 3: Initialize the client with your API key
// WHY: Authentication — proves you have access to OpenAI
// HOW: Get your key from https://platform.openai.com/api-keys
// NEVER hardcode keys in production! Use environment variables.
const client = new OpenAI({ 
  apiKey: "YOUR_API_KEY_HERE"  // Replace with your actual key
});

// ============================================
// THE CODE REVIEW FUNCTION
// ============================================

// WHY: async because we're waiting for the API response
// WHY: Takes code as a string, returns AI review as a string
async function reviewCode(code) {
  
  // WHY: Call the chat completion API
  // HOW: We specify model (gpt-3.5-turbo is fast and affordable)
  // messages: array of conversation turns
  const response = await client.chat.completions.create({
    
    model: "gpt-3.5-turbo",  // Good balance of quality and cost
    
    messages: [
      {
        // SYSTEM PROMPT — This sets the AI's persona and behavior
        // WHY: The system message defines WHO the AI is acting as
        // A good system prompt dramatically improves response quality
        role: "system",
        content: `You are a senior JavaScript developer with 10 years of experience. 
Your job is to review code written by junior developers. 
For every code review, you must provide:
1. WHAT IT DOES WELL — Two to three specific strengths
2. WHAT CAN BE IMPROVED — Three to five actionable suggestions
3. A BETTER VERSION — Rewrite the code following best practices

Be constructive, kind, and educational. Explain the WHY behind each suggestion.`
      },
      {
        // USER PROMPT — The specific code to review
        // WHY: Template literals let us inject the user's code
        role: "user",
        content: `Please review this JavaScript code thoughtfully:\n\n${code}`
      }
    ]
  });
  
  // WHY: Extract the AI's response from the API response object
  return response.choices[0].message.content;
}

// ============================================
// TEST THE TOOL — Example code that needs improvement
// ============================================

// WHY: This code has several common issues:
// - Uses 'var' instead of const/let
// - Inconsistent spacing
// - Missing semicolon consistency
// - Could be written more concisely
const myCode = `function add(a, b) {
  var result = a + b
  return result
}`;

// WHY: Call the review function and print the result
// .then() handles the Promise returned by async function
reviewCode(myCode)
  .then(review => console.log(review))
  .catch(error => console.error("Review failed:", error));
    

📜 CODE BLOCK 2: Production-Ready Version (with .env)

// PRODUCTION VERSION — Uses environment variables
// Never hardcode API keys in your source code!

// Install dotenv: npm install dotenv
// Create a .env file with: OPENAI_API_KEY=your_key_here

require("dotenv").config();
const OpenAI = require("openai");

const client = new OpenAI({ 
  apiKey: process.env.OPENAI_API_KEY
});

async function reviewCode(code, options = {}) {
  const { 
    model = "gpt-3.5-turbo", 
    temperature = 0.5   // Lower = more focused, consistent
  } = options;
  
  const response = await client.chat.completions.create({
    model: model,
    temperature: temperature,
    messages: [
      {
        role: "system",
        content: `You are a senior JavaScript developer. Review the code and provide:
1. Strengths (what works well)
2. Improvements (specific actionable feedback)
3. Refactored version with best practices`
      },
      {
        role: "user",
        content: `Review this code:\n\n${code}`
      }
    ]
  });
  
  return response.choices[0].message.content;
}
    

🤖 HOW AI ACCELERATES THIS TOPIC

Ask AI: "Improve this system prompt to get more detailed code reviews." Paste your prompt and get professional improvements.

Ask: "What are the best practices for storing and managing API keys in a Node.js application?" Learn about .env, secrets managers, and security.

Ask: "Design a prompt that makes the AI check for security vulnerabilities in JavaScript code." Extend your tool for security auditing.