weak-napi

var weak = require('weak-napi'); // We will monitor this object and invoke 'cleanup' after it's garbage collected let obj = { id: 'my-object', data: Array(1000).fill('some data string') // Make it large enough to be GC'd }; // Define the cleanup callback at a high scope to avoid strong references function cleanupCallback() { console.log('"obj" with ID ' + this.id + ' has been garbage collected!'); } // Create a weak reference to obj with the cleanup callback // Note: `this` inside the callback refers to the EventEmitter instance returned by `weak()`. const ref = weak(obj, cleanupCallback); ref.id = obj.id; // Store ID on the ref for logging in callback console.log('Weak reference created. Initial obj.id:', obj.id); // Dereference the object to allow it to be garbage collected obj = null; console.log('Original object reference cleared. Waiting for GC...'); // In a real scenario, you'd let your application run. // For demonstration, we might try to force GC, but it's not reliable or recommended. // Global.gc is usually not available unless explicitly enabled with --expose-gc. // If process.env.EXPOSE_GC is set, you can try to call it: if (typeof global.gc === 'function') { console.log('Attempting to force garbage collection...'); global.gc(); global.gc(); // Call twice for better chances } else { console.log('Run Node.js with --expose-gc flag to see immediate callback execution via global.gc().'); console.log('Otherwise, the callback will eventually fire when V8 decides to run GC naturally.'); } // Keep the process alive for a bit to allow GC to run naturally setTimeout(() => { console.log('Process ending. If GC ran, you should have seen the callback message.'); }, 500);