order points in plane to form continuous lines

order.js

const distance = (p1, p2) => (p1.x - p2.x) ** 2 + (p1.y - p2.y) ** 2;

const findNearestIndex = (point, list) => {
  let nearestDistSquared = Infinity;
  let nearestIndex;

  for (let i = 0; i < list.length; i++) {
    const curPoint = list[i];
    const distsq = distance(point, curPoint);

    if (distsq < nearestDistSquared) {
      nearestDistSquared = distsq;
      nearestIndex = i;
    }
  }

  return nearestIndex;
};

const order = (arr) => {
  const orderedList = [arr.shift()];

  while (arr.length > 0) {
    const nearestIndex = findNearestIndex(orderedList[orderedList.length - 1], arr);
    orderedList.push(arr.splice(nearestIndex, 1)[0]);
  }

  return orderedList;
};