[Put the path to the theme in Drupal.settings for use in javascript files] #d7

template.php

<?php

function mytheme_preprocess_page(&$vars) {
  // Add the path to this theme to Drupal.settings
  $setting['pathToTheme'] = path_to_theme();
  drupal_add_js($setting, 'setting');
}

// OR:

function mytheme_preprocess_page(&$vars) {
  // Add the path to this theme to Drupal.settings
  drupal_add_js('jQuery.extend(Drupal.settings, { "pathToTheme": "' . path_to_theme() . '" });', 'inline');
}

xyz.js

yepnope({
  test: Modernizr.touch,
  yep: '/' + Drupal.settings.pathToTheme + '/js/hammer.js'
});