Moving xAxis along with line

source.js

(function() {

var n = 243,
    duration = 750,
    now = new Date(Date.now() - duration),
    count = 0,
    data = d3.range(n).map(function() { return 0; });

var margin = {top: 6, right: 0, bottom: 20, left: 40},
    width = 960 - margin.right,
    height = 120 - margin.top - margin.bottom;

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.line()
    .interpolate("basis")
    .x(function(d, i) { return x(now - (n - 1 - i) * duration); })
    .y(function(d, i) { return y(d); });

var svg = d3.select("body").append("p").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
    .style("margin-left", -margin.left + "px")
  .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 axis = svg.append("g")
    .attr("class", "x axis")
    .attr("transform", "translate(0," + height + ")")
    .call(x.axis = d3.svg.axis().scale(x).orient("bottom"));

var path = svg.append("g")
    .attr("clip-path", "url(#clip)")
  .append("path")
    .datum(data)
    .attr("class", "line");

var transition = d3.select({}).transition()
    .duration(750)
    .ease("linear");

d3.select(window)
    .on("scroll", function() { ++count; });

(function tick() {
  transition = transition.each(function() {

    // update the domains
    now = new Date();
    x.domain([now - (n - 2) * duration, now - duration]);
    y.domain([0, d3.max(data)]);

    // push the accumulated count onto the back, and reset the count
    data.push(Math.min(30, count));
    count = 0;

    // redraw the line
    svg.select(".line")
        .attr("d", line)
        .attr("transform", null);

    // slide the x-axis left
    axis.call(x.axis);

    // slide the line left
    path.transition()
        .attr("transform", "translate(" + x(now - (n - 1) * duration) + ")");

    // pop the old data point off the front
    data.shift();

  }).transition().each("start", tick);
})();

Last example in http://bost.ocks.org/mike/path/

There is a error in your code, i fixed it here: http://codepen.io/atticweb/pen/GZKvgv
I don't know how i can do a pull request in gist, so that's why i did it in codepen ;)

@Atticweb Try changing the line fill, in your code-pen example, you get some strange results.

Any ideas how to fix?

.line{
fill: #ff0;
stroke: #000;
}

doesn't work with v4 :(

I forked the code pen from @Atticweb and updated to v4. Everything seems to be working properly, but I'm a little unhappy with the transition of the axis text, it doesn't respect the easing (jumpy), but the ticks transition smoothly. Any ideas?

https://codepen.io/sampaioletti/pen/eREyQZ

I'm pretty new to d3, but wanted to use this same idea in a similar project that requires v4.

Hey guys, thanks for the code.
I am trying to connect this to a webocket. I thought I'll start with random values coming through a timer:
setInterval(function(){ tick(); }, 500);
as a start . Instead of the method used in the example:

.transition().each("start", tick);

But I can't get to run smoothly: See: https://codepen.io/dtroyz/pen/YYOvEN

Any idea what I am missing ? I've tried everything I could think of/find online.
Any help would be greatly appreciated !

For anyone out there wondering what the answer is about @daniel-cohen 's issue.

I think there is a default duration when using duration(), so your code 'updates' every X ms, hence the jumpy behaviour.

Simply replace your code by .transition().duration(1).each("start",tick) 🚀