Edit - cancel.js

Edit: cancel.js

"use strict";
module.exports = function(Promise, PromiseArray, apiRejection, debug) {
var util = require("./util");
var tryCatch = util.tryCatch;
var errorObj = util.errorObj;
var async = Promise._async;

Promise.prototype["break"] = Promise.prototype.cancel = function() {
    if (!debug.cancellation()) return this._warn("cancellation is disabled");

Promise.prototype._branchHasCancelled = function() {
    this._branchesRemainingToCancel--;
};

Promise.prototype._enoughBranchesHaveCancelled = function() {
    return this._branchesRemainingToCancel === undefined ||
           this._branchesRemainingToCancel <= 0;
};

Promise.prototype._cancelBy = function(canceller) {
    if (canceller === this) {
        this._branchesRemainingToCancel = 0;
        this._invokeOnCancel();
        return true;
    } else {
        this._branchHasCancelled();
        if (this._enoughBranchesHaveCancelled()) {
            this._invokeOnCancel();
            return true;
        }
    }
    return false;
};

Promise.prototype._cancelBranched = function() {
    if (this._enoughBranchesHaveCancelled()) {
        this._cancel();
    }
};

Promise.prototype._cancel = function() {
    if (!this._isCancellable()) return;
    this._setCancelled();
    async.invoke(this._cancelPromises, this, undefined);
};

Promise.prototype._cancelPromises = function() {
    if (this._length() > 0) this._settlePromises();
};

Promise.prototype._unsetOnCancel = function() {
    this._onCancelField = undefined;
};

Promise.prototype._isCancellable = function() {
    return this.isPending() && !this._isCancelled();
};

Promise.prototype.isCancellable = function() {
    return this.isPending() && !this.isCancelled();
};

Promise.prototype._doInvokeOnCancel = function(onCancelCallback, internalOnly) {
    if (util.isArray(onCancelCallback)) {
        for (var i = 0; i < onCancelCallback.length; ++i) {
            this._doInvokeOnCancel(onCancelCallback[i], internalOnly);
        }
    } else if (onCancelCallback !== undefined) {
        if (typeof onCancelCallback === "function") {
            if (!internalOnly) {
                var e = tryCatch(onCancelCallback).call(this._boundValue());
                if (e === errorObj) {
                    this._attachExtraTrace(e.e);
                    async.throwLater(e.e);
                }
            }
        } else {
            onCancelCallback._resultCancelled(this);
        }
    }
};

Promise.prototype._invokeOnCancel = function() {
    var onCancelCallback = this._onCancel();
    this._unsetOnCancel();
    async.invoke(this._doInvokeOnCancel, this, onCancelCallback);
};

Promise.prototype._invokeInternalOnCancel = function() {
    if (this._isCancellable()) {
        this._doInvokeOnCancel(this._onCancel(), true);
        this._unsetOnCancel();
    }
};

Promise.prototype._resultCancelled = function() {
    this.cancel();
};

};

Cancel