Create Sorted Array through Instructions LeetCode solution in JavaScript

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var createSortedArray = function (instructions) {
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  let nums = [];
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  let cost = 0;
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  // define a map to track how many occurences of a number are in the array as we sort it
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  let map = {};
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  // classic binary search
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  const bin = (arr, elem) => {
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    let low = 0;
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    let high = arr.length - 1;
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    while (low <= high) {
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      let mid = (high + low) >> 1; // fancy Math.foor(high + low / 2)
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      if (arr[mid] > elem) {
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        high = mid - 1;
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      } else {
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        low = mid + 1;
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      }
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    }
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    return low;
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  };
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  // loop through the each of the values
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  for (let i of instructions) {
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    // do a binary search to determine which index this value belongs at
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    let index = bin(nums, i);
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    // insert it into the array
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    nums.splice(index, 0, i);
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    // populate a map to track how many instances of this number we have in the arr
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    if (!map.hasOwnProperty(i)) map[i] = 0;
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    // need to remove any matching numbers from the equation, meaning if the left side is 1,2,3,3
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    // and the current value is 3, we should be subtracting the existing 3's from the equation
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    let left = index - map[i];
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    // right side is the last value - index
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    let right = nums.length - 1 - index;
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    // add the min of left / right to the cost
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    cost += Math.min(left, right);
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    // increment our number occurence map
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    map[i]++;
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  }
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  const WEIRD_MOD_VAL = Math.pow(10, 9) + 7;
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  // for some goofy reason when the number is too large, send the mod val
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  return cost < 1842204555 ? cost : cost % WEIRD_MOD_VAL;
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};