檢視 MediaWiki:Common.js 的原始碼

$(function() {
  var variants = mw.config.get('wgContentLanguageVariants'); // 獲取可用的語言變體

  if (variants && variants.length > 1) {
    var currentVariant = mw.config.get('wgUserVariant');
    var languageDropdown = $('<div id="zh-variant-dropdown"></div>').append('<label for="zh-variant-select">中文：</label><select id="zh-variant-select"></select>');
    var variantSelect = languageDropdown.find('#zh-variant-select');

    for (var i = 0; i < variants.length; i++) {
      var variantCode = variants[i];
      var variantName = '';

      switch (variantCode) {
        case 'zh-tw':
        case 'zh-hant':
          variantName = '中文（繁體）';
          break;
        case 'zh-cn':
        case 'zh-hans':
          variantName = '中文（簡體）';
          break;
        default:
          variantName = variantCode;
      }

      var option = $('<option>').val(variantCode).text(variantName);
      if (variantCode === currentVariant) {
        option.prop('selected', true);
      }
      variantSelect.append(option);
    }

    variantSelect.on('change', function() {
      var selectedVariant = $(this).val();
      var currentUrl = new URL(window.location.href);
      currentUrl.searchParams.set('variant', selectedVariant);
      window.location.href = currentUrl.toString();
    });

    // 將下拉選單添加到您希望顯示的位置，例如側邊欄頂部
    $('#mw-panel').prepend(languageDropdown);

    // 或者添加到左上角 (需要 CSS 定位，如同之前的討論)
    // $('body').prepend(languageDropdown);
  }
});