d3.js - How to make svg as a layer in Leaflet.js -

recently, doing bubble map using leaflet.js. become painful when want make different layers show bubbles different colors. came 2 solutions, none of them can totally solve problems.

solution 1: problem: don't know how assign svg layer like:

var tiles = new l.layergroup();    tiles.addto(alltiles); 

i confused code:

map._initpathroot()  

here code link: http://bl.ocks.org/d3noob/9267535

solution 2: can draw different layers based on code, problem is: zoomed d3.js circles fixed in geographic location on leaflet map constant size.

here code link: http://bl.ocks.org/xevil/4921fff1d70f5601d159

i wonder have references can use? thank you.