D3从元素获取属性

var svg = d3.select("svg");
var rects = svg.selectAll("foo")
  .data(d3.range(14))
  .enter()
  .append("rect")
  .attr("fill", "teal")
  .attr("y", 20)
  .attr("x", d => 10 + 12 * d)
  .attr("height", 40)
  .attr("width", 10)
  .attr("class", d => d % 2 === 0 ? "part1" : "part2");

d3.selectAll(".part1").each(function(d,i) {
  console.log("The x position of the rect #" + i + " is " + d3.select(this).attr("x"))
})

<script src="https://d3js.org/d3.v4.min.js"></script>
<svg></svg>