I really messed up recently and I want to apologize to anyone who may have been misinformed or mislead by me. I have no idea how I came to think this nugget of unwisdom that I have been repeating. I must have read an article on it somewhere that was either wrong or maybe I just misunderstood and then began to propagate some misinformation. I have no one to blame but myself though and I feel really terrible and embarrassed about it.

It came out today during Hashrocket's live book club. I was explaining an issue I found in a codebase today where they were using contexts in jQuery to scope selectors. I was explaining that when you pass in a jQuery object as a context, the selector function ignores this parameter as it is expecting a raw DOM object.

I was called out during my monologue and as it turns out, I was dead wrong about it. One of the folks sitting in the circle looked up the jQuery API to get some more context for what I was talking about and noticed that the docs said something contrary to what I was saying. I tested it after the book club and of course it works just like the api docs say it does.

It gets even worse because I have talked about this in numerous blog posts, presentations, and conversations with other developers. The good news is that what I was saying you should do is valid, so anyone listening to me would still be writing working code.

The real problem here is that I took something on faith and didn't look it up or research it for myself. The takeaway is that reading the source code for libraries is critical. Not only will you understand exactly how the code we depend on every day works, but I guarantee you will learn something. I failed to do that in this instance and it caused quite a problem. At the very least, read the API docs before you go running your mouth.

So, to set the record straight, when you are using a context in jQuery you can pass in a raw DOM element, a jQuery object, or a Document and it will work as you expect.

Again, I am deeply sorry for confusion this has caused.