JavaScript: Check mobile browser

is_mobile.js

function is_mobile() {
       if (navigator.userAgent.match(/Android/i) ||
             navigator.userAgent.match(/webOS/i) ||
             navigator.userAgent.match(/iPhone/i) ||
             navigator.userAgent.match(/iPad/i) ||
             navigator.userAgent.match(/iPod/i) ||
             navigator.userAgent.match(/BlackBerry/) || 
             navigator.userAgent.match(/Windows Phone/i) || 
             navigator.userAgent.match(/ZuneWP7/i)
             ) {
                // some code
                return true
               }

        return false
    }