is __defineGetter__ deprecated in node.js?

Question

According to this document from MDN, Object.prototype.__defineGetter__() should not be used:

Non-standard This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

Deprecated This feature has been removed from the Web standards. Though some browsers may still support it, it is in the process of being dropped. Do not use it in old or new projects. Pages or Web apps using it may break at any time.

On the other hand, this notice mentions just the product sites facing the Web, incompatibilities between implementations, and browser support.

It clearly applies to the client-side. So, I wonder if it is also deprecated for server-side use, and what is the best alternative option.

Answer 1

__defineGetter__ and such, which were never standard, were made obsolete by ECMAScript5 (2009) by Object.defineProperty, getter/setter literal syntax in object initializers, and in ECMAScript 2015 ("ES6") by get/set declarations in classes. That syntax is deprecated even in the engines that supported it, regardless of whether the engine is being used in the browser, on a server, or in a non-web application.

Here are examples of the standard syntax. I've included setters in them as well, but of course you'd leave those off for read-only properties.

1. Object.defineProperty (ES5+, 2009):

   Object.defineProperty(obj, "name", {
       get: function() {
           return "the value";
       },
       set: function(value) {
           // Do something with value
       }
   });
   

2. Getter/setter literal syntax in object initializers (ES5+, 2009):

   var obj = {
       get name() {
           return "the value";
       },
       set name(value) {
           // Do something with value
       }
   };
   

   (I used var in that example to stick to ES5 features, but all major engines have long supported let and const.)

3. Getter/setter syntax in classes (ES2015, aka "ES6"):

   class Example {
       get name() {
           return "the value";
       }
       set name(value) {
           // Do something with value
       }
   }
   

Those are all long-supported by all major JavaScript engines (including those used by the vast majority of server-side environments [V8 in Node.js and Deno; JavaScriptCore in Bun]).

New code should use these rather than the old never-standard syntax.