Change website design for mobile devices or browser resize

Question

Im sorry if this has been asked before im sure somewhere there must be an answer for this but for some or other reason I cant find it, probably using wrong search query

Answer 1

If you want to do this with pure JavaScript, here it is-

if( /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent) ) {
// some code.. 
}

Again you can do this with jquery-

$.browser.device = (/android|webos|iphone|ipad|ipod|blackberry|iemobile|opera mini/i.test(navigator.userAgent.toLowerCase()));

If you want to do this with PHP the check out this article