kenbellows

// find the element in the body with max z-index
// adapted from this StackOverflow answer by Jimmy Chandra:
//   https://stackoverflow.com/a/1118216/470925
let max, maxVal = 0
document.querySelectorAll('body *').forEach(el => {
  // get position and zIndex style values for the element
  const {position, zIndex} = document.defaultView.getComputedStyle(el)
  // skip statically positioned elements
  if (position !== 'static') {
    // parse the string value of zIndex into an integer, defaulting to 1,

kenbellows

/**
 * Clusters 2D points so each cluster can be enclosed in a circle of radius <= d.
 * Uses greedy agglomerative merging: repeatedly merge the pair of clusters whose
 * merged centroid distance is smallest, as long as the merged cluster's max
 * distance from its centroid <= d.
 *
 * @param {Array<[number, number]>} points - array of [x, y] pairs
 * @param {number} d - maximum allowed radius for any cluster
 * @returns {Array<Array<[number, number]>>} clusters
 */