Debugging & Code Quality

Writing clean, error-free JavaScript code is essential for building reliable applications. This lesson covers practical debugging techniques and best practices to maintain high code quality.

Common Debugging Techniques

• Console Logging: Use console.log() to inspect variables, outputs, and program flow.
• Debugger Statement: Insert debugger; to pause execution and inspect in browser dev tools.
• Browser DevTools: Utilize breakpoints, step execution, watch variables, and inspect call stacks.
• Error Messages: Read stack traces carefully to locate the source of errors.

// Check value and type of variable 'count'
const count = 10;
console.log('Count value:', count);
console.log('Count type:', typeof count);

Best Practices for Code Quality

• Consistent Naming: Use meaningful and consistent variable/function names.
• Modular Code: Break code into small reusable functions.
• Comments: Add comments to clarify complex logic but avoid obvious statements.
• Linting: Use tools like ESLint to catch syntax and style issues early.
• Code Formatting: Maintain consistent indentation and spacing using Prettier or editor configs.

Debugging vs. Code Quality

Common Debugging Tools in Browsers

• Chrome DevTools: Access via F12 or right-click → Inspect. Features include breakpoints, call stack, and live editing.
• Firefox Developer Tools: Similar features with unique performance and accessibility inspectors.
• VS Code Debugger: Debug Node.js code directly from the editor with breakpoints and variable watches.

function calculateArea(width, height) {
  debugger; // Execution will pause here
  return width * height;
}

const area = calculateArea(5, 4);
console.log(area);