leak.js

leak.js

var Promise = require('promise');
var weak = require('weak');

var makeCancelable = (promise) => {
  let hasCanceled_ = false;

  const wrappedPromise = new Promise((resolve, reject) => {
    promise.then((val) =>
      hasCanceled_ ? reject({isCanceled: true}) : resolve(val)
    );
    promise.catch((error) =>
      hasCanceled_ ? reject({isCanceled: true}) : reject(error)
    );
  });

  return {
    promise: wrappedPromise,
    cancel() {
      hasCanceled_ = true;
    },
  };
};

class Foo {

  constructor(promise) {
    promise.then(() => {
      console.log("then called....", this);
    });
  }
}

var resolve;

var p = new Promise((_resolve, reject) => {
  resolve = _resolve;
});

var res = makeCancelable(p);

var foo = new Foo(res.promise);
res.cancel();
res = null;
p = null;

var ref = weak(foo, function () {
  console.log("foo gc'd");
});


foo = null;

console.log("first gc", ref);
global.gc();
global.gc(); /* just in case it takes two gcs :) */
console.log("after first gc", ref);
/* no console.log... */

/* kill the resolve chain */

resolve = null;

console.log("after resolve = null", ref);
global.gc();
console.log("after second gc", ref);