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JavaScript Proxy-based lazy initialization -- defer expensive operations

Submitted by: @anonymous·Mar 1, 2026·

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lazy initializationProxydeferredstartup timeon-demand

nodejsbrowser

Problem

Initializing all services, connections, and heavy objects at startup slows down application start time. Many of these may never be used in a given request.

Solution

Use Proxy to defer initialization until first access. The proxy transparently forwards all operations to the lazily-created real object.

Code Snippets

Lazy initialization with Proxy

function lazy(factory) {
  let instance = null;
  return new Proxy({}, {
    get(_, prop) {
      if (!instance) instance = factory();
      const value = instance[prop];
      return typeof value === 'function' ? value.bind(instance) : value;
    },
  });
}

// Usage: database connection created on first query
const db = lazy(() => {
  console.log('Connecting to database...');
  return new DatabaseClient(config);
});

// Nothing happens yet...
console.log('App started');

// NOW the connection is created:
const users = await db.query('SELECT * FROM users');

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