I saw a video in which Crockford told us not to use the new keyword. He said to use Object.create instead if I'm not mistaken. Why does he tell us not to use new if he has used it in achieving prototypal inheritance in this article that he wrote: .html

I would expect him to use Object.create instead of new, like this:

function object(o) {
    return Object.create((function() {}).prototype = o);
}

So why is it that he still uses new?

I saw a video in which Crockford told us not to use the new keyword. He said to use Object.create instead if I'm not mistaken. Why does he tell us not to use new if he has used it in achieving prototypal inheritance in this article that he wrote: http://javascript.crockford./prototypal.html

I would expect him to use Object.create instead of new, like this:

function object(o) {
    return Object.create((function() {}).prototype = o);
}

So why is it that he still uses new?

• javascript

• 1 Maybe he learned something since that video/article? It's hard to know without the video/context. – alexn Commented Nov 20, 2011 at 16:30
• 2 Probably a bination of A) Object.create not being supported across a handful of browsers, and B) that article having been written several years ago; his programming style, like most of ours, has probably changed and evolved since then. – Rob Hruska Commented Nov 20, 2011 at 16:32
• Here's the video: youtube./watch?v=hQVTIJBZook (I don't know exactly where in the video he said that, sorry) – David G Commented Nov 20, 2011 at 16:32
• 1 Also, in the article you reference, his addendum on 2008-04-07 essentially answers this, where he defines Object.create if it doesn't exist. You'd only have to use new that one time (defining Object.create). – Rob Hruska Commented Nov 20, 2011 at 16:40
• 1 As of November 2017, Douglas Crockford says he has stopped using new, Object.create(), and this: youtu.be/DxnYQRuLX7Q?t=29m6s – ESV Commented Jul 3, 2018 at 0:26

2 Answers 2

Crockford discusses new and Object.create in this Nov 2008 message to the JSLint. mailing list. An excerpt:

If you call a constructor function without the new prefix, instead of creating and initializing a new object, you will be damaging the global object. There is no pile time warning and no runtime warning. This is one of the language’s bad parts.

In my practice, I pletely avoid use of new.

This is a really old question, but…

When Crockford wrote the article you mention and the discussion linked by Paul Beusterien, there was no Object.create. It was 2008 and Object.create was, at most, a proposal (or really rarely implemented in browsers).

His final formulation is basically a polyfill:

if (typeof Object.create !== 'function') {
    Object.create = function (o) {
        function F() {}
        F.prototype = o;
        return new F();
    };
}

newObject = Object.create(oldObject);

His only use of new is, therefore, to simulate (or emulate) what Object.create must do.

He doesn’t advise us to use it. He presents a polyfill that uses it, so you don’t have to use it anywhere else.