JavaScript Technology Stack & Build System

JavaScript/Node.js Development Environment

Build Tools & Dependencies

• Runtime: Node.js (LTS version recommended)
• Package Manager: npm
• Testing Framework: Jest
• Code Formatting: Prettier
• Linting: Biome (or ESLint)
• SDK Version: AWS SDK for JavaScript v3

Common Build Commands

# Dependencies
npm install                        # Install dependencies
npm ci                            # Clean install from package-lock.json

# Testing
npm test                          # Run all tests
npm run test:unit                 # Run unit tests
npm run test:integration          # Run integration tests

# Code Quality
npm run lint                      # Lint code
npm run format                    # Format code with Prettier

# Execution
node src/hello-{service}.js       # Run hello scenario
npm start                         # Run main application

JavaScript-Specific Pattern Requirements

File Naming Conventions

• Use kebab-case for file names
• Service prefix pattern: {service}-action.js (e.g., s3-list-buckets.js)
• Hello scenarios: hello-{service}.js (e.g., hello-s3.js)
• Test files: {service}-action.test.js

Hello Scenario Structure

• File naming: hello-{service}.js or hello function in main module
• Function structure: Async function as main entry point
• Documentation: Include JSDoc comments explaining the hello example purpose

Code Structure Standards

• Module system: Use ES6 modules (import/export) or CommonJS (require/module.exports)
• Function naming: Use camelCase for function names
• Constants: Use UPPER_SNAKE_CASE for constants
• Classes: Use PascalCase for class names
• Async/Await: Use async/await for asynchronous operations

Error Handling Patterns

import { S3Client, ListBucketsCommand } from "@aws-sdk/client-s3";

const client = new S3Client({ region: "us-east-1" });

async function listBuckets() {
    try {
        const command = new ListBucketsCommand({});
        const response = await client.send(command);
        
        console.log("Buckets:", response.Buckets);
        return response.Buckets;
    } catch (error) {
        if (error.name === "NoSuchBucket") {
            console.error("Bucket not found:", error.message);
        } else if (error.name === "AccessDenied") {
            console.error("Access denied:", error.message);
        } else {
            console.error("AWS SDK Error:", error.message);
        }
        throw error;
    }
}

export { listBuckets };

Testing Standards

• Test framework: Use Jest with appropriate matchers
• Integration tests: Mark with appropriate test descriptions
• Async testing: Use async/await in test functions
• Mocking: Use Jest mocks for unit tests when appropriate
• Test naming: Use descriptive test names explaining test purpose

Project Structure

src/
├── hello-{service}.js
├── {service}-actions.js
├── {service}-scenarios.js
└── tests/
    ├── {service}-actions.test.js
    └── {service}-integration.test.js

Package.json Configuration

{
  "name": "{service}-examples",
  "version": "1.0.0",
  "type": "module",
  "scripts": {
    "test": "jest",
    "test:unit": "jest --testPathPattern=unit",
    "test:integration": "jest --testPathPattern=integration",
    "lint": "biome check .",
    "format": "prettier --write ."
  },
  "dependencies": {
    "@aws-sdk/client-{service}": "^3.0.0",
    "@aws-sdk/credential-providers": "^3.0.0"
  },
  "devDependencies": {
    "jest": "^29.0.0",
    "prettier": "^3.0.0",
    "@biomejs/biome": "^1.0.0"
  }
}

Documentation Requirements

• JSDoc comments: Use /** for function and class documentation
• Parameter documentation: Document parameters with @param
• Return documentation: Document return values with @returns
• Example documentation: Include @example blocks
• README sections: Include npm setup and execution instructions

AWS SDK v3 Specific Patterns

Client Configuration

import { S3Client } from "@aws-sdk/client-s3";
import { fromEnv } from "@aws-sdk/credential-providers";

const client = new S3Client({
    region: process.env.AWS_REGION || "us-east-1",
    credentials: fromEnv(), // Optional: explicit credential provider
});

Command Pattern Usage

import { S3Client, PutObjectCommand } from "@aws-sdk/client-s3";

const client = new S3Client({ region: "us-east-1" });

async function uploadObject(bucketName, key, body) {
    const command = new PutObjectCommand({
        Bucket: bucketName,
        Key: key,
        Body: body,
    });
    
    return await client.send(command);
}

Language-Specific Pattern Errors to Avoid

• ❌ NEVER use snake_case for JavaScript identifiers
• ❌ NEVER forget to handle Promise rejections
• ❌ NEVER mix callback and Promise patterns
• ❌ NEVER ignore proper error handling for AWS operations
• ❌ NEVER skip npm dependency management

Best Practices

• ✅ ALWAYS use kebab-case for file names
• ✅ ALWAYS use camelCase for JavaScript identifiers
• ✅ ALWAYS use async/await for asynchronous operations
• ✅ ALWAYS include proper error handling for AWS service calls
• ✅ ALWAYS use AWS SDK v3 command pattern
• ✅ ALWAYS include comprehensive JSDoc documentation
• ✅ ALWAYS handle environment variables for configuration

Environment Configuration

• AWS Region: Use AWS_REGION environment variable
• Credentials: Support AWS credential chain (environment, profile, IAM roles)
• Configuration: Use environment variables for service-specific settings

Integration with Knowledge Base

Before creating JavaScript code examples:

1. Query coding-standards-KB for "JavaScript-code-example-standards"
2. Query JavaScript-premium-KB for "JavaScript implementation patterns"
3. Follow KB-documented patterns for project structure and module organization
4. Validate against existing JavaScript examples only after KB consultation