Simple caching in Javascript using the new Logical nullish assignment (??=) operator

simple-caching-logical-nullish-assignment.js

// Simple caching in Javascript using the new Logical nullish assignment (??=) operator

class FibClass {
  // Private field to store a value
  #fib = null

  // Fibonacci sequence method (recursive calculation)
  f (n) {
    return n < 3 ? 1 : this.f(n - 1) + this.f(n - 2)
  } 

  // Getter that caches and retrieves a value
  get fib () {
    // If null, assign to #fib a calculated value and return it
    // Otherwise return the cached value
    return this.#fib ??= this.f(40)
  }
}

// Make an instance of FibClass
const fibClass = new FibClass()

// Get the value (this performs an expensive calculation)
fibClass.fib

// Get it again (this returns the now cached value instantly)
fibClass.fib