D3 Examples - Animate line and points

xxxxxxxxxx
 
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
  
 
  <style>
    path {
      stroke-width: 2px;
      fill: none;
    }
  </style>
​
  
</head>
<body>
  
  
  
  <div id="line"></div>
  <script src="https://d3js.org/d3.v4.min.js"></script>
  
  <script type="text/javascript">
    
    console.clear()    
    
    var w = 700;
    var h = 300; 
    var m = 40;
    
    var max = 10
    var numberOfSeries = 3
​
    var svg = d3.select("#line")
      .append("svg")
      .attr("width", w + m + m)
      .attr("height", h + m + m)
    
    var chart = svg.append("g")
        .attr("transform", "translate(" + m + "," + m + ")")
​
    var data = []
        
    for (var a = 0; a < numberOfSeries; a++) {
      data.push([])
      for (var i = 0; i <= max; i++) {
        data[a].push(Math.random() * max)
      }
    }
        
    
    console.log(data)
​
    var x = d3.scaleLinear()
    .domain([0, max])
    .range([0, w]);
    
    var y = d3.scaleLinear()
    .domain([0, max])
    .range([h, 0]);
    
    var line = d3.line()
      .x(function(d,i) {return x(i);})
      .y(function(d) {return y(d);})
        .curve(d3.curveCardinal)
    
    var series = chart.selectAll(".series")
        .data(data)
        .enter()
        .append("g")
    
    var bkdPath = series.append("path")
      .attr("d", d => line(d))
      .style("stroke", "lightgrey")
    
    var path = series.append("path")
      .attr("d", d => line(d))
        .attr("id", (d, i) => "path-" + i)
      .style("stroke", "orange")
        .style("stroke-width", "5px")
    
    var bkdCircle = series.selectAll(".bkd-circle")
      .data(d => d)
        .enter()
        .append("g")
        .attr("transform", function(d, i){
        return "translate(" + x(i) + "," + y(d) + ")"
      })
        .attr("class", "bkd-circle")
            .append("circle")
        .attr("r", 5)
        .style("stroke", "lightgrey")
        .style("fill", "white")
    
    var dataPoint = series.selectAll('.data-point')
        .data(d => d)
        .enter()
        .append("g")
        .attr("transform", function(d, i){
        return "translate(" + x(i) + "," + y(d) + ")"
      })
        .attr("class", "data-point")
        .attr("id", (d, i) => "data-point-" + i)
        .style("opacity", 0)
    
    dataPoint.append("circle")
        .attr("r", 5)
    
    dataPoint.append("text")
        .text((d, i) => i + ", " + round2dp(d) )
        .attr("dy", 18)
    
    
    let pointArray = []  
    let sampleRate = 100
    let sampleWidth = w / sampleRate
    
    for (var p = 0; p < numberOfSeries; p++) {
      
      pointArray.push([])
      let currentLength = 0
      let pathID = "#path-" + p
      let thisPath = d3.select(pathID)
      let node = thisPath.node()
      let pathLength = node.getTotalLength()
      let s = 0
      
      thisPath.attr("stroke-dasharray", pathLength + " " + pathLength)
            .attr("stroke-dashoffset", pathLength)
     
      for (var j = 0; j<pathLength; j++){
        let point = node.getPointAtLength(j)
        //console.log(point)
        if (point.x >= (sampleWidth * s)) {
          pointArray[p].push({"x": point.x, "y": point.y, "len": j})
          s = s + 1
        }
      }
      
      pointArray[p].push({"x": w, "y": y(data[p][data[p].length-1]), "len": pathLength})
      
      
    }
    
    //console.log(pointArray)
    
   let transitionElements = chart.selectAll(".t-elements")
    .data(pointArray)
   .enter()
    .append("g")
    
 
    
    transitionElements.selectAll(".markers")
        .data(d => d)
        .enter()
        .append("circle")
        .attr("cx", d => d.x)
        .attr("cy", d => d.y)
        .attr("r", 2)
        .style("fill", "red")
    
  
    let head = transitionElements.append("circle")
        .datum(d => d)
        .attr("cx", d => d[0].x)
        .attr("cy", d => d[0].y)
        .attr("r", 15)
        .style("fill", "green")
        .attr("id", "head")
     
    let tIndex = 0
    let dur = 50000
    
    function transitionChart(){
      tIndex =  tIndex + 1
      if (tIndex >= (sampleRate+1)) {
        
      } else {
        
        
​
        path.transition()
            .duration(dur / (sampleRate + 1))
            .ease(d3.easeLinear)
            .attr("stroke-dashoffset", function(d,i){
            let len = d3.select(this).node().getTotalLength()
            return len -pointArray[i][tIndex].len
            })
        
        head.transition()
          .duration(dur / (sampleRate + 1))
          .ease(d3.easeLinear)
          .attr("cx", (d,i) => pointArray[i][tIndex].x)
          .attr("cy", (d,i) => pointArray[i][tIndex].y)
          .on("end", transitionChart)  
      }
      
    }
    
    transitionChart()
​
 
    function round2dp(n) {
      return Number.parseFloat(n).toFixed(2);
    }
    
    
  </script>
</body>
</html>
    