JS function decoration example

decorator-meaning.js

function checkPermissionDecorator(f) {
  return function() {
    if (isAdmin()) {
      return f.apply(this, arguments);
    }
    alert( 'Недостаточно прав' );
  }
}

function save() { ... }

save = checkPermissionDecorator(save);
// save() invocation now checks permission;