How do I change the color of path in D3.js?

Question

I am creating some paths ina tree-graph in D3 and I'd like to change the color of the lines (paths), but I can't make my code work:

 // Enter any new links at the parent's previous position.
      link.enter().insert("svg:path", "g")
          .attr("class", "link")
          .attr("d", function(d) {
            var o = {x: source.x0, y: source.y0};
            return diagonal({source: o, target: o});
          })
        .transition()
          .duration(duration)
          .attr("d", diagonal);

      // Transition links to their new position.
      link.transition()
          .duration(duration)
          .attr("d", diagonal);

      // Transition exiting nodes to the parent's new position.
      link.exit().transition()
          .duration(duration)
          .attr("d", function(d) {
            var o = {x: source.x, y: source.y};
            return diagonal({source: o, target: o});
          })
          .remove();

I tried using the following to change and I've look-up up a few other solution, but I can't really understand what I need to select in my update selection to change it.

  link.selectAll("path")
      .attr("stroke", "#000000");

Thanks for the help in advance.

Answer 1

I'm just starting with d3 myself, but I think you need to use link.style("stroke",#xxxxxx).

Answer 2

An svg can change the color by using fill attribute (same is complex for path attribute even though its children of svg)

  svg
    .data([newValue])
    .transition()
    .duration(1500)
    .attr('fill', function(d) { return color(d); })

Working code for your reference:
https://jsfiddle.net/pjrc0yy3/1/