[Solved]-How to add a fixed range vertical line to a D3.js chart-d3.js

You can do this by appending a separate line that has the appropriate y coordinates:

svg.append("line")
   .attr("y1", y(0))
   .attr("y2", y(100))
   .attr("x1", ...)
   .attr("x2", ...)

where the coordinates for x1 and x2 are the same and determine the position of the vertical line.