system.js

(function ($) {

/**
 * Show/hide the 'Email site administrator when updates are available' checkbox
 * on the install page.
 */
Drupal.hideEmailAdministratorCheckbox = function () {
  // Make sure the secondary box is shown / hidden as necessary on page load.
  if ($('#edit-update-status-module-1').is(':checked')) {
    $('.form-item-update-status-module-2').show();
  }
  else {
    $('.form-item-update-status-module-2').hide();
  }

  // Toggle the display as necessary when the checkbox is clicked.
  $('#edit-update-status-module-1').change( function () {
    $('.form-item-update-status-module-2').toggle();
  });
};

/**
 * Internal function to check using Ajax if clean URLs can be enabled on the
 * settings page.
 *
 * This function is not used to verify whether or not clean URLs
 * are currently enabled.
 */
Drupal.behaviors.cleanURLsSettingsCheck = {
  attach: function (context, settings) {
    // This behavior attaches by ID, so is only valid once on a page.
    // Also skip if we are on an install page, as Drupal.cleanURLsInstallCheck will handle
    // the processing.
    if (!($('#edit-clean-url').length) || $('#edit-clean-url.install').once('clean-url').length) {
      return;
    }
    var url = settings.basePath + 'admin/config/search/clean-urls/check';
    $.ajax({
      url: location.protocol + '//' + location.host + url,
      dataType: 'json',
      success: function () {
        // Check was successful. Redirect using a "clean URL". This will force the form that allows enabling clean URLs.
        location = settings.basePath +"admin/config/search/clean-urls";
      }
    });
  }
};

/**
 * Internal function to check using Ajax if clean URLs can be enabled on the
 * install page.
 *
 * This function is not used to verify whether or not clean URLs
 * are currently enabled.
 */
Drupal.cleanURLsInstallCheck = function () {
  var url = location.protocol + '//' + location.host + Drupal.settings.basePath + 'admin/config/search/clean-urls/check';
  // Submit a synchronous request to avoid database errors associated with
  // concurrent requests during install.
  $.ajax({
    async: false,
    url: url,
    dataType: 'json',
    success: function () {
      // Check was successful.
      $('#edit-clean-url').attr('value', 1);
    }
  });
};

/**
 * When a field is filled out, apply its value to other fields that will likely
 * use the same value. In the installer this is used to populate the
 * administrator e-mail address with the same value as the site e-mail address.
 */
Drupal.behaviors.copyFieldValue = {
  attach: function (context, settings) {
    for (var sourceId in settings.copyFieldValue) {
      $('#' + sourceId, context).once('copy-field-values').bind('blur', function () {
        // Get the list of target fields.
        var targetIds = settings.copyFieldValue[sourceId];
        // Add the behavior to update target fields on blur of the primary field.
        for (var delta in targetIds) {
          var targetField = $('#' + targetIds[delta]);
          if (targetField.val() == '') {
            targetField.val(this.value);
          }
        }
      });
    }
  }
};

/**
 * Show/hide custom format sections on the regional settings page.
 */
Drupal.behaviors.dateTime = {
  attach: function (context, settings) {
    for (var value in settings.dateTime) {
      var settings = settings.dateTime[value];
      var source = '#edit-' + value;
      var suffix = source + '-suffix';

      // Attach keyup handler to custom format inputs.
      $('input' + source, context).once('date-time').keyup(function () {
        var input = $(this);
        var url = settings.lookup + (settings.lookup.match(/\?q=/) ? '&format=' : '?format=') + encodeURIComponent(input.val());
        $.getJSON(url, function (data) {
          $(suffix).empty().append(' ' + settings.text + ': <em>' + data + '</em>');
        });
      });
    }
  }
};

 /**
 * Show/hide settings for page caching depending on whether page caching is
 * enabled or not.
 */
Drupal.behaviors.pageCache = {
  attach: function (context, settings) {
    $('#edit-cache-0', context).change(function () {
      $('#page-compression-wrapper').hide();
      $('#cache-error').hide();
    });
    $('#edit-cache-1', context).change(function () {
      $('#page-compression-wrapper').show();
      $('#cache-error').hide();
    });
    $('#edit-cache-2', context).change(function () {
      $('#page-compression-wrapper').show();
      $('#cache-error').show();
    });
  }
};

})(jQuery);