A bunch of bugs to take care of if you’re going to target legacy IE browsers.
The ‘change’ event doesn’t always fire. Not for checkboxes, radios, multi-select lists. Use the click handler instead.
Clicking label with input inside doesn’t focus the input.
An element’s ‘opacity’ value isn’t propagated to its positioned descendants.
Collection of cheat sheets on the HTML language, tags, xpath, browsers behaviours ...