pipeline.js

// Realization

function startPipeline(pipelineRequests, order) {
  order = order || [
      'before',
      'requestModel',
      'after',
      'stateToModel',
      'setValidations'
  ];

  return order.reduce((acc, task) => acc.then(
    previosResponse => {
      if (typeof pipelineRequests[task] === 'function') {
        return pipelineRequests[task](previosResponse)
      }
      return previosResponse;
    }
  ), Promise.resolve(null));

}

// MOCK

function apiRequest(val) {
    return new Promise((res, rej) => {
        setTimeout(() => res(val), Math.random()*1000)
    })
}

// EXAMPLE USAGE

const result = startPipeline({

    before: () => {
      return apiRequest(1)
    },

    requestModel: (previosResponse) => {
      console.log(previosResponse); return apiRequest(previosResponse + 1)
    },

    after: (previosResponse) => {
      console.log(previosResponse);
      return apiRequest(previosResponse + 1)
    },

    stateToModel: (previosResponse) => {
      console.log(previosResponse);
      return apiRequest(previosResponse + 1)
    },

});

result.then(res => console.log('result_0:', res))


// Optional custom order

const result2 = startPipeline({

    one: () => {
      return apiRequest(1)
    },

    two: (previosResponse) => {
      console.log(previosResponse);
      return apiRequest(previosResponse + 1)
    },

    three: (previosResponse) => {
      console.log(previosResponse);
      return apiRequest(previosResponse + 1)
    },

}, ['three', 'two', 'one']);


result2.then(res => console.log('result_1:', res))