d3 corrected verlet

d3-verlet.js

function tick() {
    var i, n = nodes.length, node;

    alpha += (alphaTarget - alpha) * alphaDecay;
    iterations++;

    forces.each(function(force) {
      force(alpha);
    });

    //for (i = 0; i < n; ++i) {
    //  node = nodes[i];
    //  if (node.fx == null) node.x += node.vx *= velocityDecay;
    //  else node.x = node.fx, node.vx = 0;
    //  if (node.fy == null) node.y += node.vy *= velocityDecay;
    //  else node.y = node.fy, node.vy = 0;
    //}

    // corrected verlet
    const intertia = 0.5;
    const timeStep = 1;
    for (let i = 0; i < n; i++) {
      const node = nodes[i];
      const acc = 0.5 * (timeStep * timeStep);
      const prevX = node.x, prevY = node.y;
      const px = node.px, py = node.py;

      const vx = intertia * (prevX - px);
      const vy = intertia * (prevY - py);

      node.x = prevX + vx + node.vx * acc;
      node.y = prevY + vy + node.vy * acc;

      node.px = prevX; node.py = prevY;
      node.vx = node.vy = 0;
    }
  }