Formating numbers and dates in Spanish

index.js

import { timeFormatLocale } from 'd3-time-format';
import { formatLocale } from 'd3-format';
// You need 'rollup-plugin-json' in rollup.config.js
import es from 'd3-format/locale/es-ES.json';
import ES from 'd3-time-format/locale/es-ES.json';

export default function() {
  var locale = timeFormatLocale(ES);
  var formatted = formatLocale(es).format;
  var f = formatted('2,');

  var months = function(date) {
    var str = locale.format('%B')(date);
    return str[0].toUpperCase() + str.substring(1, str.length);
  };
}