document.contains / Node.contains polyfill?

[Dmitry Iv.]

Is there a polyfill for Node.contains? IE doesn’t support it so far.

It may look something like this:

    Node.prototype.contains = function(el){
        while (el = el.parentNode) {
            if (el === this) return true;
        }
        return false;
    }

[Jonathan Neal]

Good call. I'll put a polyfill together.

Prepare yourself for slight disappointment, because contains returns true if a node is a descendant of a given node or the node itself (and they didn't mention that). It's silly, but document.contains(document) is true, and document.body.contains(document.body) is true. You can try it for yourself, in Chrome or IE.

Internet Explorer has supported something like Element.prototype.contains since IE5. In fact, in IE11 document.body.contains === HTMLElement.prototype.contains is true.

So, the polyfill for Node.prototype.contains targets document.contains. I'm mentioning this because the polyfill for older IE will actually target Element and Document. Older IE cannot polyfill Node because text nodes can't be polyfilled.

[Dmitry Iv.]

Ok, thanks for research.

[Jonathan Neal]

@dfcreative it's in. thanks so much for finding this.