https://leetcode.com/problems/island-perimeter/

islandPerimiter.js

var islandPerimeter = function(grid) {    
    const countWateryNeighbors = (row, col) => {
        return [[row+1, col],[row-1, col],[row, col+1],[row, col-1]]
        .map(([r, c]) => {
            if(r < 0 || r >= grid.length || c < 0 || c >= grid[0].length) return 1;
            if(grid[r][c] === 0) return 1;
            return 0;
        })
        .reduce((a, b) => a + b);
    };
    
    let result = 0;
    for(let row = 0; row < grid.length; row++){
        for(let col = 0; col < grid[0].length; col++){
            result += grid[row][col] ? countWateryNeighbors(row, col) : 0;
        }
    }
    return result;
};