clip path example

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }

</style>
</head>

var holder = d3.select("body") // select the 'body' element
      .append("svg")           // append an SVG element to the body
      .attr("width", 449)      // make the SVG element 449 pixels wide
      .attr("height", 249);    // make the SVG element 249 pixels high

// draw a circle
holder.append("clipPath")       // define a clip path
	.attr("id", "ellipse-clip") // give the clipPath an ID
  .append("ellipse")            // shape it as an ellipse
	.attr("cx", 175)            // position the x-centre
	.attr("cy", 100)            // position the y-centre
	.attr("rx", 100)            // set the x radius
	.attr("ry", 50); 
    
holder.append("rect")
	.attr("x",175)
	.attr("y",100)
	.attr("clip-path","url(#ellipse-clip)")
	.attr("fill","SteelBlue")
	.attr("height",100)
	.attr("width",200)
    
  </script>
</body>

https://d3js.org/d3.v4.min.js