According to many site owners, PDF documents and external links should open in a new window. Markdown makes it relatively hard to specify this. This script automates this for you, so you do not have to worry about this.

How it works

This script detects external links and links to PDF files, using plain javascript. It automagically adds ‘target=”_blank”’ to these links. This is done by the following code.


//open external links in a new window
function external_new_window() {
    for(var c = document.getElementsByTagName("a"), a = 0;a < c.length;a++) {
        var b = c[a];
        if(b.getAttribute("href") && b.hostname !== location.hostname) {
   = "_blank";
            b.rel = "noopener";
//open PDF links in a new window
function pdf_new_window ()
    if (!document.getElementsByTagName) return false;
    var links = document.getElementsByTagName("a");
    for (var eleLink=0; eleLink < links.length; eleLink ++) {
    if ((links[eleLink].href.indexOf('.pdf') !== -1)||(links[eleLink].href.indexOf('.doc') !== -1)||(links[eleLink].href.indexOf('.docx') !== -1)) {
        links[eleLink].onclick =
        function() {
            return false;



Step 1. Download the file new-window-fix.html
Step 2. Save the file in the ‘_includes’ directory of your project
Step 3. Make sure the bottom of your layout document looks like this:

{% include new-window-fix.html %}