Drupal 8  8.0.2
/var/www/d8/core/modules/quickedit/js/util.js

Converts a field id into a formatted url path.

Drupal.quickedit.util.buildUrl( 'node/1/body/und/full', '/quickedit/form/!entity_type/!id/!field_name/!langcode/!view_mode' );

Parameters
{string}id The id of an editable field.
{string}urlFormat The Controller route for field processing.
Returns
{string} The formatted URL.