D3 Realtime Areaspline

by JP Obley

HTML

<div id="time"></div>

CSS

.axis path, .axis line {
    fill: none;
    stroke: #000;
    shape-rendering: crispEdges;
}
.line {
    fill: dodgerblue;
}
text {
    font-size: 12px;
    fill: #5a5a5a;
}

JavaScript

(function () {

    var n = 10,
        duration = 10000,
        now = new Date(Date.now() - duration),
        count = 0,
        data = d3.range(n).map(function () {
            return 0;
        });

    var margin = {
        top: 20,
        right: 0,
        bottom: 20,
        left: 40
    },
    width = 600 - margin.right - margin.left,
        height = 400 - margin.top;

    var x = d3.time.scale()
        .domain([now - (n - 2) * duration, now - duration])
        .range([0, width]);

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

    var line = d3.svg.area()
        .interpolate("basis")
        .x(function (d, i) {
        return x(now - (n - 1 - i) * duration);
    })
        .y0(height)
        .y1(function (d, i) {
        return y(d);
    });

    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 + ")");

    svg.append("defs").append("clipPath")
        .attr("id", "clip")
        .append("rect")
        .attr("width", width)
        .attr("height", height);

    var xAxis = svg.append("g")
        .attr("class", "x axis")
        .attr("transform", "translate(0," + y(0) + ")")
        .call(x.axis = d3.svg.axis().scale(x).orient("bottom"));

    var yAxis = svg.append("g")
        .attr("class", "y axis")
        .call(d3.svg.axis().scale(y).orient("left"));

    var path = svg.append("g")
        .attr("clip-path", "url(#clip)")
        .append("path")
        .data([data])
        .attr("class", "line");
    var text = svg.select("text").attr("font-size", 10);
    var timeDiv = d3.select("#time");
    tick();

    function tick() {
        // update the domains
        now = new Date();
        timeDiv.html(now.getHours() + ":" + now.getMinutes() + ":" + now.getSeconds());
      
        x.domain([now - (n - 2) * duration, now...