Adding a vertical line to a D3 chart, that follows the mouse pointer.

d3-mouse-over-line.js

var vertical = d3.select(".chart")
      .append("div")
      .attr("class", "remove")
      .style("position", "absolute")
      .style("z-index", "19")
      .style("width", "1px")
      .style("height", "380px")
      .style("top", "10px")
      .style("bottom", "30px")
      .style("left", "0px")
      .style("background", "#fff");

d3.select(".chart")
    .on("mousemove", function(){  
       mousex = d3.mouse(this);
       mousex = mousex[0] + 5;
       vertical.style("left", mousex + "px" )})
    .on("mouseover", function(){  
       mousex = d3.mouse(this);
       mousex = mousex[0] + 5;
       vertical.style("left", mousex + "px")});