You can use these functions:
function shareOnFB(){
var url = "https://www.facebook.com/sharer/sharer.php?u=https://yoururl.com&t=your message";
window.open(url, '', 'menubar=no,toolbar=no,resizable=yes,scrollbars=yes,height=300,width=600');
return false;
}
function shareOntwitter(){
var url = 'https://twitter.com/intent/tweet?url=URL_HERE&via=getboldify&text=yourtext';
TwitterWindow = window.open(url, 'TwitterWindow',width=600,height=300);
return false;
}
function shareOnGoogle(){
var url = "https://plus.google.com/share?url=https://yoururl.com";
window.open(url, '', 'menubar=no,toolbar=no,resizable=yes,scrollbars=yes,height=350,width=480');
return false;
}
<a onClick="shareOnFB()"> Facebook </a>
<a onClick="shareOntwitter()"> Twitter </a>
<a onClick="shareOnGoogle()"> Google </a>