Number of Operations to Make Network Connected LeetCode solution in JavaScript

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/**
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 * @param {number} n
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 * @param {number[][]} connections
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 * @return {number}
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 */
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class UnionFind {
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  constructor(n) {
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    this.root = new Array(n).fill().map((_, index) => index);
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    this.components = n;
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  }
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  find(x) {
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    if (x == this.root[x]) return x;
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    return (this.root[x] = this.find(this.root[x]));
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  }
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  union(x, y) {
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    const rootX = this.find(x);
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    const rootY = this.find(y);
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    if (rootX != rootY) {
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      this.root[rootY] = rootX;
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      this.components--;
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    }
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  }
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}
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var makeConnected = function (n, connections) {
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  // We need at least n - 1 cables to connect all nodes (like a tree).
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  if (connections.length < n - 1) return -1;
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  const uf = new UnionFind(n);
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  for (const [a, b] of connections) {
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    uf.union(a, b);
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  }
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  return uf.components - 1;
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};