微信里如何判断页面被分享成功

var shareData = {
img_url: "",
img_width: 200,
img_height: 200,
link: '',
desc: '',
title: '',
appid: 0
};

document.addEventListener('WeixinJSBridgeReady', function onBridgeReady() {
// 发送给好友
WeixinJSBridge.on('menu:share:appmessage', function(argv){
shareFriend();
});
// 分享到朋友圈
WeixinJSBridge.on('menu:share:timeline', function(argv){
shareTimeline();
});
}, false);

function shareTimeline() {
WeixinJSBridge.invoke('shareTimeline', shareData, function(res) {
validateShare(res);
_report('timeline', res.err_msg);
});
}

function shareFriend() {
WeixinJSBridge.invoke('sendAppMessage', shareData, function(res) {
validateShare(res);
_report('send_msg', res.err_msg);
});
}

function validateShare(res) {
if(res.err_msg != 'send_app_msg:cancel' && res.err_msg != 'share_timeline:cancel') {
//分享完毕回调
}
}