Promise Cancellation Example

cancel-promise.js

// to run:
// $ npm install bluebird
// $ node cancel-promise.js

// example from: http://openmymind.net/Cancelling-Long-Promise-Chains/

(function () {
  'use strict';

  var Promise = require('bluebird');

  function a(v) {
    return Promise.resolve(v);
  }

  function b(v) {
    return v * 2;
  }

  function c(v) {
    return v * 2;
  }

  function chain(v) {
    var p = a(v)
      .then(function (value) {
        console.log(value);
        if (!value) {
          return p.cancel();
        }
        return b(value);
      })
      .then(function (value) {
        console.log(value);
        return c(value);
      })
      .cancellable()
      .catch(Promise.CancellationError, function () {
        console.log('cancelled!');
        return 0;
      });
    return p;
  }

  Promise.resolve()
    .then(function () {

      console.log('--------------------------------------------------------------------------------');
      console.log('Chain [1]');
      console.log('--------------------------------------------------------------------------------');
      return chain(1)
        .then(function (v) {
          console.log('Chain [1]: %s', v); // will print 4
        })
        .catch(function (err) {
          console.error('Chain [1] Error', err); // won't be called
        });

    })
    .then(function () {

      console.log('--------------------------------------------------------------------------------');
      console.log('Chain [undefined]');
      console.log('--------------------------------------------------------------------------------');
      return chain(undefined) // same as saying `return chain()`, but I'm being explicit for illustration purposes
        .then(function (v) {
          console.log('Chain [undefined]: %s', v); // will print 0 because of cancellation handler
        })
        .catch(function (err) {
          console.error('Chain [undefined] Error', err); // won't be called
        });

    });

}());

Are you sure it works? When I try to run it I get Unhandled rejection TypeError: a(...).then(...).then(...).cancellable is not a function error. Nothing changes even if I add the following lines:
Promise.config({cancellable: true});

What's missing?

I tried

 'use strict';
var Promise =  require('bluebird');
Promise.config({
    cancellation :true
});

var myPromise = function(param){
    return new Promise(function(resolve,reject){
        if(param == null){
            return reject(new Error("rejected"));
        }
        setTimeout(function(){
           return resolve("resolved");
        },1000);

    })
}

var promise = myPromise("param");

//var promise = myPromise();

//console.log(promise);
promise
.then(function(message){
   console.log("message:",message); 
   promise.cancel();
   console.log(promise.isCancellable()); //returns false
   //throw new Promise.CancellationError("cancelled");
})
//.cancellable()
// .catch(function(err){
//    console.log("error",err);
// })
.then(function(message){
   //console.log("message",message);
   console.log("then 1 called");
})
.then(function(){
    console.log("then 2 called");
})
.catch(function(err){
    console.log("Error:",err);
})
.catch(Promise.CancellationError,function(err){
    console.log("cancelleation Error",err);
});

Response :

message: resolved
false
then 1 called
then 2 called