How to handle deprecation warnings in Node.js?

# Run with no warnings
node --no-deprecation app.js

# Throw on deprecation
node --throw-deprecation app.js

# Show stack trace
node --trace-deprecation app.js

const util = require('util');

// Deprecated function
const oldFunction = util.deprecate(
  function oldFunction() {
    return 'old result';
  },
  'oldFunction() is deprecated. Use newFunction() instead.',
  'DEP0001'
);

oldFunction(); // Shows warning once

process.on('warning', (warning) => {
  console.log('Name:', warning.name);
  console.log('Message:', warning.message);
  console.log('Code:', warning.code);
  console.log('Stack:', warning.stack);
});

// Suppress specific warnings
const originalEmit = process.emit;
process.emit = function(name, data, ...args) {
  if (name === 'warning' && data.code === 'DEP0001') {
    return false; // Suppress
  }
  return originalEmit.apply(process, [name, data, ...args]);
};

# Silence all deprecations
NODE_NO_WARNINGS=1 node app.js