user24/wtf.js

(the parseInt was a desperate attempt to ensure that the value is completely divorced from the code that follows, omitting it still produces the odd behaviour. Also yeah it should be parseFloat).

This code, OTOH, works perfectly - the icons stay in the same place but are now absolutely positioned there:

                    $('#calendar .barIcons > .barIcon').each(function (i, icon) {
                        $(icon).css({
                            "left": $(icon).position().left
                        });
                    }).css({
                        "position": "absolute"
                    });

While this breaks (all lefts are set to zero):

                $('#calendar .barIcons > .barIcon').each(function (i, icon) {
                    $(icon).css({
                        "position": "absolute",
                        "left": $(icon).position().left
                    });
                });

I'm not sure alert(..) is guaranteed to have to run synchronously. I think a browser could be free to defer it to happen at the end of the function. Not positive on that, but it's one way to explain the behavior you're seeing. I've seen this before in Chrome with console.log(..) as well.

(The CSS and structure of the page shouldn't even make a difference - I just can't see how the position().left could POSSIBLY be affected by the position: absolute; it's value must have been resolved BEFORE the position absolute is applied.)

@getify yeah I know console.log can be async - didn't think alert could. But even then, it is actually setting the values to zero too, even without the alert.