nested-immutable-arrays

import { fromJS } from 'immutable';

const initialState = fromJS({
  panes: [{
    title: 'abc',
    service: '',
    tagName: '',
    preDefinedApi: '',
    methodType: '',
    url: '',
    urlParams: [{
      label: '',
      name: '',
      value: '',
    }],
    headers: [{
      label: '',
      name: '',
      value: '',
    }],
  }],
  activePane: '0'
});

case ADD_PANE:
      var obj = {
        title: 'New Tab',
        service: 'ser',
        tagName: '',
        preDefinedApi: '',
        methodType: '',
        url: '',
        urlParams: [{
          label: '',
          name: '',
          value: '',
        }],
        headers: [{
          label: '',
          name: '',
          value: '',
        }],
      };
      return state.updateIn(['panes'], arr => arr.push(fromJS(obj)));//pushing an immutable object to an immutable array

    case CHANGE_SERVICE:
      var activePane = state.get('activePane');//getting index of nested object in Array(panes) that will be modified below...
      return state.setIn(['panes', parseInt(activePane), 'service'], action.val);