'undefined' from .attr() causes potential breaking chaining issues in overload setter/getter

[mr.leon.yu@…]

With advent of jQuery 1.6, which returns undefined in .attr(), the occurrence of undefined in jQuery code has become ever more prevalent. This can cause a lot more existing code to break. The for example the following code:

$('element').attr('title', $('element2').attr('alt')).css('color', '#000');

In the above code, if $('element2').attr('alt') returns a value, the code would run fine. However, in 1.6, when $('element2').attr('alt') is undefined, the line would break because it would turn the setter call into an getter call. In turn the getter call would stop the chaining from working.

Solution: Make sure arguments.length == 1 before assuming the call is a getter call.

[ajpiano]

Even before 1.6, the fact that a setter would act like a getter if the value you passed as the second argument was unexpectedly undefined was... unexpected and confusing to users. I concur with the OP that we should probably check arguments.length here.

[Rick Waldron]

I agree that this should be handled more like other user programming errors (quietly, discretely) but it still stands that if you know there is a possibility of that attr call returning undefined, you should be handling it in your own code. it's fixable with four characters:

$('element').attr('title', $('element2').attr('alt') || '' ).css('color', '#000');

[Rick Waldron]

A further look at the history of the test suite reveals _many_ tests written to specifically support this expectation