Animated Spiral - Triangle

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Triangles</title>

<style>

line {
            stroke: #000;
            stroke-width: 3px;
            stroke-opacity: 1;
        }

</style>

</head>
<body>

const width = 960;
    const height = 500;
    const length = 200;
    const iterations = 20;
    const duration = 400;

let svg = d3.select('body').append('svg')
        .attr('width', width)
        .attr('height', height)
        .attr('overflow', 'hidden');

let x = Math.round(length*Math.cos(30*Math.PI/180)*1000)/1000;
    let y = Math.round(length*Math.sin(30*Math.PI/180)*1000)/1000;

let g = svg.append('g')
        .attr('transform', 'translate(' + width/2 + ',' + height/2 + ')');

let triangle = [
        {'x1': x, 'y1': y, 'x2': 0, 'y2': -length},
        {'x1': 0, 'y1': -length, 'x2': -x, 'y2': y},
        {'x1': -x, 'y1': y, 'x2': x, 'y2': y}
    ];

let container = g.append('g');

container.append('g').selectAll('line')
        .data(triangle)
        .enter().append('line')
        .attr('x1', function (d) {return d.x1; })
        .attr('y1', function (d) {return d.y1; })
        .attr('x2', function (d) {return d.x2; })
        .attr('y2', function (d) {return d.y2; });

spiral(container, iterations);
    let lineData = ripMultiGLineData(container);

let start = Date.now() - (duration+100);
    d3.timer(animate);

function animate() {
        let t = (Date.now() - start)/(duration+100);
        if(t > 1) {
            twist(container, duration, lineData);
            start = Date.now();
        }
    }

</script>

</body>
</html>

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