The standard way to do this in Drupal is with drupal_add_jsdrupal_add_js()
, using the "setting" type, e.g.:
drupal_add_js(array('variableName' => 'value'), 'setting');
drupal_add_js(array('variableName' => 'value'), 'setting');
That will make the variable available on the JS side at Drupal.settings.variableNameDrupal.settings.variableName
.