As you have it, this is not possible because your links are just normal HTML links. When the new page opens in a new tab, the current page will not have any reference to it and so cannot change it in any way. You will need to open the page using javascript and set the title that way.

You can dynamically set this up in window onload to find all a tags and add a click event whihc opens the window and sets the title.

If you want different titles for each page, you can store this in a data- attribute in the a tag.

Note tho that this will only work with pages in the same domain (for security), and that it does not handle people right clicking and pressing "Open in New Window". Middle click in Windows does seem to work however.

HTML

<a href="test.html" data-title="A new page" target="_blank">open me</a>

JavaScript

window.addEventListener("load", function() {

    // does the actual opening
    function openWindow(event) {
        event = event || window.event;

        // find the url and title to set
        var href = this.getAttribute("href");
        var newTitle = this.getAttribute("data-title");
        // or if you work the title out some other way...
        // var newTitle = "Some constant string";

        // open the window
        var newWin = window.open(href, "_blank");

        // add a load listener to the window so that the title gets changed on page load
        newWin.addEventListener("load", function() {
            newWin.document.title = newTitle;
        });

        // stop the default `a` link or you will get 2 new windows!
        event.returnValue =  false;
    }

    // find all a tags opening in a new window
    var links = document.querySelectorAll("a[target=_blank][data-title]");
    // or this if you don't want to store custom titles with each link
    //var links = document.querySelectorAll("a[target=_blank]");

    // add a click event for each so we can do our own thing
    for(var i = 0; i < links.length; i++) {
        links[i].addEventListener("click", openWindow.bind(links[i]));
    }

});

Sample JsFiddle

This is a trick,

function openInNewTab(url) {
  window.open(url, '_blank').focus();
}

// Or just
window.open(url, '_blank').focus();

In most cases, this should happen directly in the onclick handler for the link to prevent pop-up blockers, and the default "new window" behavior. You could do it this way, or by adding an event listener to your DOM object.

<div onclick="openInNewTab('www.test.com');">Something To Click On</div>

Reference: Open a URL in a new tab using JavaScript

Try this:

  ....
  var newWindow = window.open(newdata, "_blank");
  newWindow.document.title = "Some title";
  ....

EDIT:

Another way to do this might be to send an iframe to a new window instead of opening it directly with the base64 string.

So something like:

var newWindow = window.open();
newWindow.document.write('<iframe src="data:application/pdf;base64,' + (strData) + '" frameborder="0" allowfullscreen></iframe>');
newWindow.document.title = "Your Title Here";