It's slowly outdated.

I discovered a year ago that similar Such statements have been unable to run in IE7.0 and Firefox, while the old version of the tour and some other IE kernel browser can also be, presumably by the developers deliberately blocked off. As the browser upgrades, the success rate of this statement is getting lower and higher, I find some new articles on the Internet are still in use.
Advice or early habits it, this way most browsers can be implemented.