CODESAMPLE

Lazy Initialization - TypeScript

Lazy Initialization TypeScript

The Lazy Initialization pattern delays the creation of an expensive object until it is actually needed. This improves startup performance because resources aren’t allocated unnecessarily. The provided TypeScript code uses a simple closure to encapsulate the initialization logic. The getInstance function checks if instance has already been created; if not, it performs the initialization (simulated by a delay and console log) and stores the result in the instance variable for subsequent calls. This approach is common in TypeScript for managing singleton-like behavior and optimizing resource usage, and utilizes its support for closures effectively.

// LazyInitialization.ts

class ExpensiveObject {
  constructor() {
    console.log("ExpensiveObject created!");
    // Simulate a costly operation
    for (let i = 0; i < 1000000; i++) {
      // Some dummy operation
    }
    console.log("ExpensiveObject initialized.");
  }

  doSomething() {
    console.log("Doing something with ExpensiveObject...");
  }
}

let instance: ExpensiveObject | null = null;

function getInstance(): ExpensiveObject {
  if (!instance) {
    instance = new ExpensiveObject();
  }
  return instance;
}

// Example Usage
// First call - initializes the object
const obj1 = getInstance();
obj1.doSomething();

// Subsequent calls - return the existing instance
const obj2 = getInstance();
obj2.doSomething();

console.log(obj1 === obj2); // true - same instance