Popup blockers try to tell when a window is being opened in direct response to a user action or spontaneously by the application. The way they probably do this is by checking whether the function that called window.open() was run in response to a user-triggered event like a mouse click.

When you perform a synchronous AJAX request, the function that was triggered by the mouse click is still running when the response arrives and the success function calls window.open. So it's considered to be a user-requested window, not a popup.

When you use asynchronous AJAX, the click handler is no longer running when the success function runs. The asynchronous call to window.open is considered spontaneous by the browser, so it blocks it.

I don't think there's any way around this, because anything you could do could also be used by everyone else to get around popup blockers, and they would be useless.

Great answer sfdcfox, using modals is definitively the better way to go!

In addition, for some cases, the window methods can be still useful:

• window.open() and window.location() display a confirmation dialog to ask the user if they would like to navigate away from the current domain. This is in an effort to prevent phishing attacks, e.g. salesforce.com -> saelsforce.com.
• window.close() should work as expected, just remember that scripts may not close windows that were not opened by them.

I hope this helps!

You can pass arguments to showModalDialog function. Simply pass window object as an argument.

window.showModalDialog(theURL, window);

Yo can access the arguments from the modal window using dialogArguments. See: http://msdn.microsoft.com/en-us/library/ms533723%28VS.85%29.aspx

var openerWindow = window.dialogArguments;

Use

const yourWindow = window.open();
yourWindow.opener = null;
yourWindow.location = "http://someurl.here";

Credit goes to Mathias Bynens: https://mathiasbynens.github.io/rel-noopener/

        <td>
        <form>
        <select name="menu1" id="menu1">
            <option selected="selected" value="">...</option>
            <option value="ListArchivedProjects">List archived projects</option>
            <option value="ListArchivedCertificates">List archived certificates</option>
            <option value="SelectProject">List Projects</option>
            <option value="ListCertificates">List Certificates</option>
            <option value="AddProjectForm.jsp">+ Add new project</option>
            <option value="AddCertificateForm.jsp">+ Add new certificate</option>
        </select>
          <script type="text/javascript">
              var urlmenu.onchange = function() {
              window.open( this.options[ this.selectedIndex ].value, '_self');
               };
        </script>
        </form>
    </td>

A window.open equivalent is below

var w = window.open('', '', 'width=400,height=400,resizeable,scrollbars');
w.document.write('Content goes here');
w.document.close();

Use it according to your need.