Guess Number Higher or Lower LeetCode solution in JavaScript

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/**
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 * Forward declaration of guess API.
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 * @param {number} num   your guess
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 * @return 	     -1 if num is higher than the picked number
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 *			      1 if num is lower than the picked number
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 *               otherwise return 0
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 * var guess = function(num) {}
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 */
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/**
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 * @param {number} n
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 * @return {number}
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 */
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var guessNumber = function (n) {
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  let lower = 1;
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  let higher = n;
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  while (lower <= higher) {
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    let mid = Math.floor((lower + higher) / 2);
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    if (guess(mid) == 0) {
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      return mid;
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    } else if (guess(mid) == -1) {
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      higher = mid - 1;
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    } else {
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      lower = mid + 1;
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    }
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  }
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  return 0;
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};