react-mapfilter/src/selectors/date_field.js

A React Component for viewing and filtering GeoJSON

import { createSelector } from 'reselect'

import getFieldAnalysis from './field_analysis'
import {FIELD_TYPE_DATE} from '../constants'

/**
 * Pick the date field that appears in most records
 */
const getDateFieldName = createSelector(
  getFieldAnalysis,
  (fieldAnalysis) => {
    let dateField
    for (let fieldname in fieldAnalysis.properties) {
      const field = fieldAnalysis.properties[fieldname]
      if (field.type !== FIELD_TYPE_DATE) continue
      if (!dateField || field.count > dateField.count) {
        dateField = field
      }
    }
    return dateField && dateField.fieldname
  }
)

export default getDateFieldName