Practical Generator Use Cases

Generators have numerous real-world applications beyond simple iteration. This section explores practical scenarios where generators shine.

When to Use Generators

Use Case	Why Generators
Lazy evaluation	Compute values only when needed
Infinite sequences	Represent endless streams of data
State machines	Maintain state between steps
Custom iteration	Complex traversal logic
Async flow control	Pause/resume async operations

Key Points

• Generators provide memory efficiency for large datasets.
• They enable clean representation of algorithms with internal state.
• Generators are ideal for data pipelines and transformations.
• They can simplify async code when combined with promises.

Example Code

// 1. Lazy evaluation with large datasets
function* lazyRange(start, end, step = 1) {
  for (let i = start; i <= end; i += step) {
    yield i;
  }
}

// Processing only first 5 odd numbers without generating all numbers
const oddNumbers = lazyRange(1, Infinity, 2);
let count = 0;
for (const num of oddNumbers) {
  console.log(num); // 1, 3, 5, 7, 9
  count++;
  if (count >= 5) break;
}

// 2. Infinite sequence: Fibonacci
function* fibonacci() {
  let a = 0, b = 1;
  while (true) {
    yield a;
    [a, b] = [b, a + b];
  }
}

const fib = fibonacci();
console.log(fib.next().value); // 0
console.log(fib.next().value); // 1
console.log(fib.next().value); // 1
console.log(fib.next().value); // 2
console.log(fib.next().value); // 3
console.log(fib.next().value