(function(d, s, id) { var js, fjs = d.getElementsByTagName(s)[0]; if (d.getElementById(id)) return; js = d.createElement(s); js.id = id; js.src = "https://connect.facebook.net/vi_VN/sdk/xfbml.customerchat.js"; fjs.parentNode.insertBefore(js, fjs); }(document, 'script', 'facebook-jssdk'));