olivesnews/js/nouislider-year-format.js

(function (Drupal) {
  "use strict";

  Drupal.behaviors.nouisliderYearFormat = {
    attach: function (context, settings) {
      const sliderEl = context.querySelector("#year.noUi-target");

      if (!sliderEl || !sliderEl.noUiSlider) return;

      // Prevent re-running if we've already patched this slider
      if (sliderEl.dataset.yearFormatApplied) return;
      sliderEl.dataset.yearFormatApplied = "true";

      const integerFormat = {
        to: function (value) {
          return String(Math.round(value));
        },
        from: function (value) {
          return Math.round(Number(value));
        },
      };

      sliderEl.noUiSlider.updateOptions({
        format: integerFormat,
        tooltips: [integerFormat, integerFormat],
        ariaFormat: integerFormat,
      });
    },
  };
})(Drupal);