if (screen.width == 320) {
    window.location.href = "/MobileSite/320/Default.aspx"	//填寫要轉向的位址
}
else if ((screen.width >= 240) && (screen.width < 320)) {
    window.location.href = "/MobileSite/240/Default.aspx"	//填寫要轉向的位址
}
else if ((screen.width >= 176) && (screen.width < 240)) {
    window.location.href = "/MobileSite/176/Default.aspx"	//填寫要轉向的位址
}