Web applications: react to the slopes of the iphone

Many are afraid to write applications for iphone, for fear of difficulties. In fact, there is nothing complicated about it.
Today I will touch on the topic of how your website responds to the slopes of the device.
Let's take a look at the code, which is plain javascript:
// ,
function updateOrientation()
{
var orientation=window.orientation;
switch(orientation)
{
case 0:
alert(" ");
case 90:
alert(" ");
case -90:
alert(" ");
}
}

window.onorientationchange=updateOrientation; //

Do you still think that there is something complicated about it? Welcome to Apple Developer Center
UPDATE: if someone is interested - I will tell you a little more about interesting, but a bit more tedious things. About the screen resolution, how to make your application was of normal size and not have to be brought closer, the principles of the interface, etc.