lewisdale.dev/config/filters/dates.js

module.exports = function(eleventyConfig) {
  eleventyConfig.addFilter('parseDate', dateString => new Date(dateString));

  eleventyConfig.addFilter('dateDisplay', date => new Date(date).toLocaleDateString('en-GB', {
    "dateStyle": "short"
  }));

  eleventyConfig.addFilter('dateTimeDisplay', date => new Date(date).toLocaleString('en-GB', {
    'dateStyle': 'short',
    'timeStyle': 'short',
  }));

  eleventyConfig.addFilter('timeDisplay', date => new Date(date).toLocaleTimeString('en-GB', {
    'hour': '2-digit',
    'minute': 'numeric',
    'hour12': true
  }));

  // eleventyConfig.addFilter('rfc3339', date => new Date(date).toISOString());
}