Javascript targeting Safari only

We often say Safari and Chrome are the same in terms of HTML and CSS behaviours but it’s not always the case. Here is a bit of javascript to target Safari only. 

Chrome has both ‘Chrome‘ and ‘Safari‘ inside userAgent string.
Safari has only ‘Safari‘.

In native javascript:

var is_chrome = navigator.userAgent.indexOf('Chrome') > -1;
var is_explorer = navigator.userAgent.indexOf('MSIE') > -1;
var is_firefox = navigator.userAgent.indexOf('Firefox') > -1;
var is_safari = navigator.userAgent.indexOf("Safari") > -1;
var is_opera = navigator.userAgent.toLowerCase().indexOf("op") > -1;
if ((is_chrome)&&(is_safari)) { is_safari = false; }
if ((is_chrome)&&(is_opera)) { is_chrome = false; }

Usage:
if (is_safari) { alert('Safari'); }

Or for Safari only, use this :

if (navigator.userAgent.indexOf('Safari') != -1 && navigator.userAgent.indexOf('Chrome') == -1) {alert('Its Safari');}

Source: http://stackoverflow.com/questions/5899783/detect-safari-chrome-ie-firefox-opera-with-user-agent