weighted-quick-union.js

var items = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];

var parent = [];

var size = [];

for (i = 0; i < items.length; ++i){
  parent[i] = i;
  size[i] = 1;
}

var find = function (p) {
  while (p != parent[p]) {
    p = parent[p];
  }
  return p;
};

var union = function (p, q) {
  var rootP = find(p);
  var rootQ = find(q);
  
  if (rootP == rootQ) return;
  
  // make smaller root point to larger one
  if (size[rootP] < size[rootQ]) {
    parent[rootP] = rootQ;
    size[rootQ] += size[rootP];
  }
  else {
    parent[rootQ] = rootP;
    size[rootP] += size[rootQ];
  }
  
  console.log(parent);
};

console.log(parent);