How to draw line with arrow using d3.js

Question

I have trouble in drawing the line with arrow using d3.js. I did see some tutorials and wrote this code, but I just see the line with no arrow mark. Could anyone please look at it and tell me where am I missing. Thanks in advance.

var w = 300;
var h = 300;
var svg = d3.select("body")
  .append("svg")
  .attr("width", w)
  .attr("height", h);

//arrow
svg.append("svg:defs")
  .append("svg:marker")
  .attr("id", "triangle")
  .attr("viewBox", "0 -5 10 10")
  .attr("refX", 15)
  .attr("refY", -1.5)
  .attr("markerWidth", 6)
  .attr("markerHeight", 6)
  .attr("orient", "auto");

//line              
svg.append("line")
  .attr("x1", 100)
  .attr("y1", 100)
  .attr("x2", 200)
  .attr("y2", 100)          
  .attr("stroke-width", 1)
  .attr("stroke", "black")
  .attr("marker-end", "url(#triangle)");

Answer 1

Change your marker creation to the following:

svg.append("svg:defs").append("svg:marker")
    .attr("id", "triangle")
    .attr("refX", 15)
    .attr("refY", -1.5)
    .attr("markerWidth", 6)
    .attr("markerHeight", 6)
    .attr("orient", "auto")
    .append("path")
    .attr("d", "M 0 -5 10 10")
    .style("stroke", "black");

Once you do this, you'll see a line being drawn. You may want to use fill instead of stroke if you want a filled in arrow, which you can get by using the following code:

svg.append("svg:defs").append("svg:marker")
    .attr("id", "triangle")
    .attr("refX", 6)
    .attr("refY", 6)
    .attr("markerWidth", 30)
    .attr("markerHeight", 30)
    .attr("orient", "auto")
    .append("path")
    .attr("d", "M 0 0 12 6 0 12 3 6")
    .style("fill", "black");