WeakCounter

A weak map that counts occurrences of object keys.

Similar to Counter but uses WeakMap as the base, allowing garbage collection of keys.

@example

// Track reference counts for DOM elements
const elementRefs = new WeakCounter<HTMLElement>()

function addReference(element: HTMLElement) {
  elementRefs.increment(element)
  console.log(`References: ${elementRefs.get(element)}`)
}

function removeReference(element: HTMLElement) {
  elementRefs.decrement(element)
  console.log(`References: ${elementRefs.get(element)}`)
}

const div = document.createElement('div')
addReference(div)     // References: 1
addReference(div)     // References: 2
removeReference(div)  // References: 1

@example

// Count object interactions without preventing garbage collection
const objectInteractions = new WeakCounter<object>()

function handleInteraction(obj: object, count = 1) {
  objectInteractions.increment(obj, count)
}

const user = { id: 1, name: 'Alice' }
const session = { sessionId: 'abc123' }

handleInteraction(user, 3)
handleInteraction(session, 1)
handleInteraction(user, 2)

console.log(objectInteractions.get(user))     // 5
console.log(objectInteractions.get(session))  // 1
// When user and session are no longer referenced elsewhere,
// they can be garbage collected along with their counts

@example

// Initialize with existing counts
const cache1 = {}
const cache2 = {}
const cache3 = {}

const hitCounter = new WeakCounter<object>([
  [cache1, 10],
  [cache2, 5],
  [cache3, 15]
])

hitCounter.increment(cache1, 3)  // 10 -> 13
console.log(hitCounter.get(cache1))  // 13
console.log(hitCounter.get(cache2))  // 5