For Facebook we use this Onclick event in the Facebook share button →
<a onClick="window.open('http://www.facebook.com/sharer.php?s=100&p[title]=YOUR_TITLE&p[summary]=YOUR_DESCRIPTION&p[url]=YOUR_URL&p[images][0]=YOUR_IMAGE','sharer','toolbar=0,status=0,width=580,height=325');" href="javascript: void(0)"> Facebook </a>
The above practically works like a charm.
Can someone help me for its Twitter, Google Plus, and the Pinterest equivalent?