iPad doesn’t trigger resize event going from vertical to horizontal?

If I understood you correctly, you want to do something when the user tilts the iPad. Here you go:

window.onorientationchange = function(){

    var orientation = window.orientation;

    // Look at the value of window.orientation:

    if (orientation === 0){

        // iPad is in Portrait mode.

    }

    else if (orientation === 90){

        // iPad is in Landscape mode. The screen is turned to the left.

    }


    else if (orientation === -90){

        // iPad is in Landscape mode. The screen is turned to the right.

    }

}