file.js

/**
 * @file
 * Provides JavaScript additions to the managed file field type.
 *
 * This file provides progress bar support (if available), popup windows for
 * file previews, and disabling of other file fields during Ajax uploads (which
 * prevents separate file fields from accidentally uploading files).
 */

(function ($) {

/**
 * Attach behaviors to managed file element upload fields.
 */
Drupal.behaviors.fileValidateAutoAttach = {
  attach: function (context, settings) {
    if (settings.file && settings.file.elements) {
      $.each(settings.file.elements, function(selector) {
        var extensions = settings.file.elements[selector];
        $(selector, context).bind('change', {extensions: extensions}, Drupal.file.validateExtension);
      });
    }
  },
  detach: function (context, settings) {
    if (settings.file && settings.file.elements) {
      $.each(settings.file.elements, function(selector) {
        $(selector, context).unbind('change', Drupal.file.validateExtension);
      });
    }
  }
};

/**
 * Attach behaviors to the file upload and remove buttons.
 */
Drupal.behaviors.fileButtons = {
  attach: function (context) {
    $('input.form-submit', context).bind('mousedown', Drupal.file.disableFields);
    $('div.form-managed-file input.form-submit', context).bind('mousedown', Drupal.file.progressBar);
  },
  detach: function (context) {
    $('input.form-submit', context).unbind('mousedown', Drupal.file.disableFields);
    $('div.form-managed-file input.form-submit', context).unbind('mousedown', Drupal.file.progressBar);
  }
};

/**
 * Attach behaviors to links within managed file elements.
 */
Drupal.behaviors.filePreviewLinks = {
  attach: function (context) {
    $('div.form-managed-file .file a, .file-widget .file a', context).bind('click',Drupal.file.openInNewWindow);
  },
  detach: function (context){
    $('div.form-managed-file .file a, .file-widget .file a', context).unbind('click', Drupal.file.openInNewWindow);
  }
};

/**
 * File upload utility functions.
 */
Drupal.file = Drupal.file || {
  /**
   * Client-side file input validation of file extensions.
   */
  validateExtension: function (event) {
    // Remove any previous errors.
    $('.file-upload-js-error').remove();

    // Add client side validation for the input[type=file].
    var extensionPattern = event.data.extensions.replace(/,\s*/g, '|');
    if (extensionPattern.length > 1 && this.value.length > 0) {
      var acceptableMatch = new RegExp('\\.(' + extensionPattern + ')$', 'gi');
      if (!acceptableMatch.test(this.value)) {
        var error = Drupal.t("The selected file %filename cannot be uploaded. Only files with the following extensions are allowed: %extensions.", {
          '%filename': this.value,
          '%extensions': extensionPattern.replace(/\|/g, ', ')
        });
        $(this).closest('div.form-managed-file').prepend('<div class="messages error file-upload-js-error">' + error + '</div>');
        this.value = '';
        return false;
      }
    }
  },
  /**
   * Prevent file uploads when using buttons not intended to upload.
   */
  disableFields: function (event){
    var clickedButton = this;

    // Only disable upload fields for Ajax buttons.
    if (!$(clickedButton).hasClass('ajax-processed')) {
      return;
    }

    // Check if we're working with an "Upload" button.
    var $enabledFields = [];
    if ($(this).closest('div.form-managed-file').length > 0) {
      $enabledFields = $(this).closest('div.form-managed-file').find('input.form-file');
    }

    // Temporarily disable upload fields other than the one we're currently
    // working with. Filter out fields that are already disabled so that they
    // do not get enabled when we re-enable these fields at the end of behavior
    // processing. Re-enable in a setTimeout set to a relatively short amount
    // of time (1 second). All the other mousedown handlers (like Drupal's Ajax
    // behaviors) are excuted before any timeout functions are called, so we
    // don't have to worry about the fields being re-enabled too soon.
    // @todo If the previous sentence is true, why not set the timeout to 0?
    var $fieldsToTemporarilyDisable = $('div.form-managed-file input.form-file').not($enabledFields).not(':disabled');
    $fieldsToTemporarilyDisable.attr('disabled', 'disabled');
    setTimeout(function (){
      $fieldsToTemporarilyDisable.attr('disabled', false);
    }, 1000);
  },
  /**
   * Add progress bar support if possible.
   */
  progressBar: function (event) {
    var clickedButton = this;
    var $progressId = $(clickedButton).closest('div.form-managed-file').find('input.file-progress');
    if ($progressId.length) {
      var originalName = $progressId.attr('name');

      // Replace the name with the required identifier.
      $progressId.attr('name', originalName.match(/APC_UPLOAD_PROGRESS|UPLOAD_IDENTIFIER/)[0]);

      // Restore the original name after the upload begins.
      setTimeout(function () {
        $progressId.attr('name', originalName);
      }, 1000);
    }
    // Show the progress bar if the upload takes longer than half a second.
    setTimeout(function () {
      $(clickedButton).closest('div.form-managed-file').find('div.ajax-progress-bar').slideDown();
    }, 500);
  },
  /**
   * Open links to files within forms in a new window.
   */
  openInNewWindow: function (event) {
    $(this).attr('target', '_blank');
    window.open(this.href, 'filePreview', 'toolbar=0,scrollbars=1,location=1,statusbar=1,menubar=0,resizable=1,width=500,height=550');
    return false;
  }
};

})(jQuery);