Javascript function hijacking [from xfocus] _ javascript skills

Javascript function hijacking, that is, the javascripthijacking technology mentioned by foreigners. A piece of code that I accidentally saw when I discussed the problem with Jian Xin
Javascript function hijacking, that is, the javascript hijacking technology mentioned by foreigners. A piece of code that was accidentally seen when I first discussed the problem with Jian Xin, probably written like this:
Window. alert = function (s ){};
I think this method is clever and novel. It is similar to API Hook. simply called javascript function hook, that is, function hijacking. By replacing the implementation of js functions to hijack this function call, an example of a complete hook alert function is as follows: