Number of Enclaves LeetCode solution in JavaScript

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/**
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 * @param {number[][]} grid
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 * @return {number}
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 */
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var numEnclaves = function (grid) {
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  let count = 0,
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    rowLength = grid.length,
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    colLength = grid[0].length;
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  const updateBoundaryLand = (row, col) => {
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    if (grid?.[row]?.[col]) {
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      grid[row][col] = 0;
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      updateBoundaryLand(row + 1, col);
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      updateBoundaryLand(row - 1, col);
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      updateBoundaryLand(row, col + 1);
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      updateBoundaryLand(row, col - 1);
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    }
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  };
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  for (let i = 0; i < rowLength; i++) {
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    if (grid[i][0] || grid[i][colLength - 1]) {
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      updateBoundaryLand(i, 0);
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      updateBoundaryLand(i, colLength - 1);
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    }
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  }
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  for (let j = 0; j < colLength; j++) {
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    if (grid[0][j] || grid[rowLength - 1][j]) {
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      updateBoundaryLand(0, j);
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      updateBoundaryLand(rowLength - 1, j);
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    }
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  }
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  for (let i = 0; i < rowLength; i++) {
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    for (let j = 0; j < colLength; j++) {
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      if (grid[i][j]) count++;
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    }
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  }
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  return count;
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};