isElement

[john]

Build a function that can test for isElement, some tests to consider:

window // should fail
document // should fail
document.body
document.body.childNodes // should fail
document.body.firstChild // fail, text node
document.body.firstChild.nextSibling // fail, comment
document.getElementsByTagName("form")[0]
document.getElementsByTagName("form")[0].elements // fail, array
document.getElementsByTagName("object")[0]

[anonymous]

Why is this "wontfix"? After all there is $.isWindow and $.isXMLDoc. I'd implement it like this: $.isElement = function (e) { return !!(e && e.nodeType === 1); };

[dmethvin]

If you profile a largeish jQuery app/site, you'll answer your own question. We test for something being a specific DOM nodeType a lot, often in tight loops. Even today you'll see that the cursed .isXMLDoc() comes up near the top of many profiles so we don't want another bottleneck. If we're not going to use it internally then it should be a plugin.