Like button example

like-button.js

<div class="fb-like" data-href="http://example.com/" data-send="true" data-layout="button_count" data-width="450" data-show-faces="true"></div>
<div id="fb-root"></div>
<script>
  window.fbAsyncInit = function() {
    // init the FB JS SDK
    FB.init({
      status     : true, // check the login status upon init?
      cookie     : true, // set sessions cookies to allow your server to access the session?
      xfbml      : true  // parse XFBML tags on this page?
    });

    // Additional initialization code such as adding Event Listeners goes here

  };

  // Load the SDK's source Asynchronously
  // Note that the debug version is being actively developed and might
  // contain some type checks that are overly strict.
  // Please report such bugs using the bugs tool.
  (function(d, debug){
     var js, id = 'facebook-jssdk', ref = d.getElementsByTagName('script')[0];
     if (d.getElementById(id)) {return;}
     js = d.createElement('script'); js.id = id; js.async = true;
     js.src = "//connect.facebook.net/en_US/all" + (debug ? "/debug" : "") + ".js";
     ref.parentNode.insertBefore(js, ref);
   }(document, /*debug*/ false));
</script>