svg_javascript_html5_tips.txt

1. When drawing links from source to target, make sure that the link simply touches the target. 
   This will make the arrow-head at the end of the link visible.

          .attr("x1", function(d) { return d.source.x_ * width + nodeW / 2 ; })
          .attr("y1", function(d) { return d.source.y_ * height + nodeH / 2 ; })
          .attr("x2", function(d) { return d.target.x_ * width + nodeW / 2 + nodeW / 2 * Math.sign(d.source.x_ - d.target.x_); })
          .attr("y2", function(d) { return d.target.y_ * height + nodeH / 2 + nodeH / 2 * Math.sign(d.source.y_ - d.target.y_); })

2. If you want to insert text in a rectangle, the text and the rect elements should be siblings. https://stackoverflow.com/a/5450269
   To keep the text within the rect, specify the following attributes:
          .attr("dominant-baseline", "hanging")
          .text(function (d){ return d.id; })
          .attr("x", function (d){ return d.x_ * width + rectRound; })
          .attr("y", function (d){ return d.y_ * height ; })