2. Small multiple area chart

<!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;
        }
        
        svg {
            font: 10px sans-serif;
        }
        
        .line {
            fill: none;
            stroke: black;
            stroke-width: 2px;
            .area {
                fill: lightsteelblue;
            }
        }

</style>
</head>

<body>
    <script>
        var margin = {
                top: 40,
                right: 40,
                bottom: 40,
                left: 40
            },
            width = 500, //interieur
            height = 300; //interieur

var x = d3.scaleTime().range([0, width]),
            y = d3.scaleLinear().range([height / 4, 0]),
            c = d3.scaleOrdinal(d3.schemeCategory10);

//https://www.d3noob.org/2013/01/filling-area-under-graph.html
        var area = d3.area()
            .x(function(d) {
                return x(d.date)
            })
            .y0(height / 4) // Ordonnées en bas (height car l'origine est en haut à gauche)
            .y1(function(d) {
                return y(d.price)
            });

d3.text('stocks.csv', function(error, raw) {

var dsv = d3.dsvFormat(',')
            var data = dsv.parse(raw);

// Nest stock values by symbol.
            var nested_data = d3.nest()
                .key(function(d) {
                    return d.symbol;
                })
                .entries(data);

// Parse and caculate some values for each nested_data
            nested_data.forEach(function(s) {
                s.values.forEach(function(d) {
                    d.date = d3.timeParse("%b %Y")(d.date);
                    d.price = +d.price;
                });

s.maxPrice = d3.max(s.values, function(d) {
                    return d.price;
                });
                s.sumPrice = d3.sum(s.values, function(d) {
                    return d.price;
                });
            });

// Create the default x-domain.
            x.domain(d3.extent(data, function(d) {
                return d.date;
            }));

// Create the container "svg" and 1 subcontainer "g" for margins.
            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 + ")");

// From the subcontainer "g", create 4 subsubcontainer "g" for each graph. 
            var g = svg.selectAll("g").data(nested_data).enter()
                .append("g")
                .attr("transform", function(d, i) {
                    return "translate(0, " + height / 4 * i + ")"
                })

// Create a path for the area.
            g.append("path")
                .attr("class", "area")
                .attr("d", function(d) {
                    y.domain([0, d.maxPrice * 1.2]); // 1.2 pour faire une marge
                    return area(d.values);
                })
                .style("fill", function(d) {
                    return c(d.key)
                })

// Display last value.
            g.append("text")
                .text(function(d, i) {
                    return d.key;
                })
                .attr("y", height / 4 / 2)
                .attr("x", width + 2)
                .style("font-family", "monospace");
        });

</script>
</body>

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