The JavaScript-free viewport tag solution.

This viewport tag...

<meta name="viewport" content="width=device-width,initial-scale=1,
   maximum-scale=1,minimum-scale=1,user-scalable=no">

 
 

...in contrast to the one I mention here will show show the screen at 1:1 scale and disallow scaling to other scales across, I assume, all devices. (It worked at my iPhone in both portrait and landscape modes, switching between the two just fine.) What I mention here is still worth a look however as it includes the setInterval polling which it pretty neat in its own right.

setInterval("my_function();",500);