How to declare XML namespace in Javascript for xlink:href and download the SVG file

Question

I have a D3JS tree that I want to download as SVG. I am successful in downloading and rendering the SVG file if I use the following code and parse it to replace the first <g> and last </g> with <svg></svg> tags:

$('#download-SVG').click(function() {
var dl = document.createElement('a');
document.body.appendChild(dl); // This line makes it work in Firefox.
dl.setAttribute("href", svgDataURL(svg.node()));
dl.setAttribute("download", "test.svg");
dl.click();
});

I replaced the createElement and setAttribute with createElementNS and setAttributeNS as in the code below:

$('#download-SVG').click(function() {
    var dl = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
    dl.setAttribute('viewBox', '-2500 -420 6000 10000');
    dl.setAttribute("width", "100%");
    dl.setAttribute("height", "100%");
    dl.setAttributeNS('http://www.w3.org/1999/xlink', 'href', svgDataURL(svg.node()));
    document.body.appendChild(dl); // This line makes it work in Firefox.
    dl.setAttribute("download", "test.svg");
    dl.click();
   });

function svgDataURL(svg) {
    var svgAsXML = (new XMLSerializer).serializeToString(svg);
    var dataURL = "data:image/svg+xml," + encodeURIComponent(svgAsXML);
    return dataURL;
   }

The SVG tags are inserted correctly, however, I get the following error if I try to open the file in Chrome:

error on line 1 at column 45779: Namespace prefix xlink for href on svg is not defined

which is due to xmlns not being declared. I have assuemed that setArrtibuteNS would do that!

A snippet from the SVG file (from Chrome Inspect):

<svg viewBox="-2500 -420 6000 10000" width="100%" height="100%" xlink:href="data:image/svg+xml,%3Cg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20transform%3D%22translate(700%2C25)scale(.7%2C.7)%22%3E%3Cpath%20class%3D%22link%22%20stroke%3D%22%23ccc% …… 3C%2Fg%3E" download="test.svg"></svg>

Also I get the error

custom.js:166 Uncaught TypeError: dl.click is not a function

which works in the original code.

Any explanation of both these would be appreciated.