如何从新窗口获取URL

var newWindow = window.open('https://www.example.com');
var newWindowURL = newWindow.location.href;
console.log(newWindowURL);

<a href="https://www.example.com" target="_blank" id="link">Open New Window</a>

<script>
    var newWindowURL = document.getElementById("link").href;
    console.log(newWindowURL);
</script>

var newWindow = window.open('https://www.example.com');

// 监听子窗口发送的消息
window.addEventListener('message', function(event) {
    if (event.origin === 'https://www.example.com') {
        var newWindowURL = event.data;
        console.log(newWindowURL);
    }
});

window.opener.postMessage(window.location.href, 'https://www.example.com');