gistfile1.js

Workflow.run = function (actions) {
    var files = [];
    var promise = Promise.resolve(files);
    actions.forEach(function(action) {
        promise = promise.then(function (outFiles) {
            // Need to return a promise here to keep the chain going
            return new Action(action, outFiles);
        });
    });
    promise = promise.catch(function (error) {
        // Do something here
    });
};