On gists

WeakMap / WeakSet

JavaScript

examples.js Raw #

// https://javascript.plainenglish.io/memory-magic-in-javascript-why-weakmaps-and-weaksets-are-your-secret-weapon-for-high-performance-62562cc24dc5

// 1. Private Data Storage Inside Classes
const privateData = new WeakMap();

class BankAccount {
  constructor(balance) {
    privateData.set(this, { balance });
  }

  getBalance() {
    return privateData.get(this).balance;
  }
}

// 2. Caching Expensive Computations
const cache = new WeakMap();
function compute(obj) {
  if (!cache.has(obj)) {
    cache.set(obj, expensiveCalculation(obj));
  }
  return cache.get(obj);
}


// 3. Avoiding Memory Leaks in DOM-based Apps
const elementData = new WeakMap();

function attachData(el, data) {
  elementData.set(el, data);
}

function getData(el) {
  return elementData.get(el);
}



// 1. Tracking Objects Without Overhead
const processedItems = new WeakSet();

function process(item) {
  if (processedItems.has(item)) return;
  // Process the item
  processedItems.add(item);
}