确定window.open()命令是否打开了aspx页面

var aspxWindow = window.open('https://example.com/mypage.aspx', '_blank');

protected void Page_Load(object sender, EventArgs e)
{
    // 在这里添加您的代码，例如：
    // Response.Write("ASPX 页面已成功加载");
}

var aspxWindow = window.open('https://example.com/mypage.aspx', '_blank');

var checkInterval = setInterval(function() {
    if (aspxWindow.closed) {
        clearInterval(checkInterval);
        console.log('ASPX 页面已成功加载');
    }
}, 1000);