registerDirective = function registerDirective(Vue, name, def) {
  if (Vue && name && def) {
    // Ensure that any leading V is removed from the
    // name, as Vue adds it automatically
    Vue.directive(name.replace(/^VB/, 'B'), def);
  }
}
Load a directive.
@param {object} Vue
@param {string} Directive name
@param {object} Directive definition