I'm pretty sure that OP knew the issue, not just you, so it's not ignorance. And it's not the moment to cite The Good Parts either. There is no failure here to

I'm pretty sure that OP knew the issue, not just you, so it's not ignorance. And it's not the moment to cite The Good Parts either. There is no failure here to be seen. There is a clever hack to make a spreadsheet shared quick and dirty. Just a reminder that all the JS code you run, in particular on jsFiddle, is untrusted and is part of the security model of the JS engine in your browser that evil JS code must not be able to do any harm. If it did, report it to the browser vendor and earn a bounty.