I noticed while working on a project that used a css selector input[readonly="readonly"] that for both readonly and disabled, the .attr function does not properly update the DOM. It puts in readonly="" and disabled="" instead of an actual value. I don't know if this was done intentionally or not, but I thought I'd bring it to the attention of the developers.

Functionally it works correctly, it's only in the case if a developer is trying to use the readonly="readonly" selector where it becomes an issue.