Linked List Cycle LeetCode solution in JavaScript

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/**
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 * Definition for singly-linked list.
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 * function ListNode(val) {
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 *     this.val = val;
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 *     this.next = null;
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 * }
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 */
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/**
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 * @param {ListNode} head
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 * @return {boolean}
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 */
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function hasCycle(head) {
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  let fast = head;
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  while (fast && fast.next) {
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    head = head.next;
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    fast = fast.next.next;
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    if (head === fast) return true;
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  }
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  //head and first pointers value in
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  //each iteration with head=[3,2,0,-4], pos = 1
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  //1st iteration: 3 3
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  //2nd iteration: 2 0
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  //3rd iteration: 0 2
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  //final iteration: -4 -4
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  return false;
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}