Finding land on Civilization 3 - http://nick.balestra.ch/2015/recursion-workshop/

continentCounter.js

function continentCounter (world, x, y) {
  var board = world.slice();

  if (board[x] === undefined || board[x][y] !== "land") {
    return 0;
  }  

  var count = 1;
  board[x][y] = "counted";
  
  // above
  count = count + continentCounter(board, x-1, y-1);
  count = count + continentCounter(board, x-1, y);
  count = count + continentCounter(board, x-1, y+1);

  // same row
  count = count + continentCounter(board, x, y-1);
  count = count + continentCounter(board, x, y+1);

  // below
  count = count + continentCounter(board, x+1, y-1);
  count = count + continentCounter(board, x+1, y);
  count = count + continentCounter(board, x+1, y+1);  
  
  return count;
}


var o = "water"; // water
var M = "land"; // land

var world = [ 
  [o,o,o,o,M,o,o,o,o,o],
  [o,o,o,M,M,o,o,o,o,o],
  [o,o,o,o,M,o,o,M,M,o],
  [o,o,M,o,M,o,o,o,M,o],
  [o,o,o,o,M,M,o,o,o,o],
  [o,o,o,M,M,M,M,o,o,o],
  [M,M,M,M,M,M,M,M,M,M],
  [o,o,M,M,o,M,M,M,o,o],
  [o,M,o,o,o,M,M,o,o,o],
  [M,o,o,o,M,M,o,o,o,o]
];

// Test
// continentCounter(world, 0, 4); // -> 32
// continentCounter(world, 3, 2); // -> 1
// continentCounter(world, 0, 0); // -> 0