Instead of using the sharer.php script on Facebook, you can use the Facebook JavaScript SDK to make a custom share dialog.
<!-- include Facebook JavaScript SDK -->
<!-- share link -->
<a href="#" class="share-btn">Share to Facebook</a>
<script type="text/javascript">
function fb_share() {
// facebook share dialog
FB.ui( {
method: 'feed',
name: "Your Page Title",
link: "https://www.webniraj.com/link-to-page/",
picture: "https://stackexchange.com/users/flair/557969.png",
caption: "Some description here"
}, function( response ) {
// do nothing
} );
}
// add click event to link using jQuery
$(document).ready(function(){
$('.share-btn').on( 'click', fb_share );
});
</script>
This will create a nice popup for sharing to Facebook, and you can easily change the title, description, and picture attributes in the JavaScript. Working demo available here.