Cut Off Trees for Golf Event LeetCode solution in JavaScript

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var cutOffTree = function (forest) {
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  const trees = forest
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    .flat()
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    .filter((x) => x && x !== 1)
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    .sort((a, b) => b - a);
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  let currPos = [0, 0],
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    totalDist = 0;
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  while (trees.length) {
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    const grid = [...forest.map((row) => [...row])];
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    const res = getDist(currPos, trees.pop(), grid);
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    if (res == null) return -1;
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    const [pos, dist] = res;
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    currPos = pos;
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    totalDist += dist;
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  }
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  return totalDist;
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  function getDist(start, target, grid) {
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    const dir = [
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      [1, 0],
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      [-1, 0],
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      [0, 1],
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      [0, -1],
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    ];
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    let queue = [start],
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      dist = 0;
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    while (queue.length) {
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      const next = [];
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      for (let [r, c] of queue) {
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        if (grid[r][c] === target) return [[r, c], dist];
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        if (!grid[r][c]) continue;
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        for (let [x, y] of dir) {
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          x += r;
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          y += c;
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          if (
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            x >= 0 &&
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            x < grid.length &&
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            y >= 0 &&
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            y < grid[0].length &&
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            grid[x][y]
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          )
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            next.push([x, y]);
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        }
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        grid[r][c] = 0;
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      }
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      dist++;
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      queue = next;
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    }
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    return null;
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  }
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};