Parabola

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
    svg { width: 100%; height: 100%; }
    path {
      fill: none;
      stroke: teal;
    }
    
    .axis path, line {
      stroke: #aaa;
      shape-rendering: crispEdges;
    }
    
    .axis text {
      fill: #aaa;
      font-size: 11px;
    }
  </style>
</head>

<body>
  <script>
    var margin = {top: 50, right: 50, bottom: 50, left: 50};
    var width = 960 - margin.left - margin.right;
    var height = 500 - margin.top - margin.bottom;
    var svg = d3.select("body").append("svg")
      .attr("width", width + margin.left + margin.right)
      .attr("height", height + margin.top + margin.bottom)
    .append("g")
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var fn = function (x) {
      return Math.pow(x, 2);
    };

var x = d3.scale.linear()
      .range([0, width]);

var y = d3.scale.linear()
      .range([height, 0]);

var xAxis = d3.svg.axis()
      .scale(x);

var yAxis = d3.svg.axis()
      .orient('left')
      .scale(y);

var line = d3.svg.line()
      .interpolate('basis')
      .x(function (d) {return x(d.x);})
      .y(function (d) {return y(d.y);});

var data = d3.range(-10, 11).map(function (d) {
      return {x:d, y:fn(d)};
    });

x.domain(d3.extent(data, function (d) {return d.x;}));
    y.domain([0, d3.max(data, function (d) {return d.y;})]);

svg.append('g')
      .attr('class', 'axis')
      .attr('transform', 'translate(0,' + height + ')')
      .call(xAxis);

svg.append('g')
      .attr('class', 'axis')
      .attr('transform', 'translate(' + width/2 + ',0)')
      .call(yAxis);

svg.append('path')
      .datum(data)
      .attr('d', line);

</script>
</body>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js