Mapping land

map.js

/*

So let's say we're writing a program that will find the number of islands given a picture from a satellite. 
The picture has already been pre-processed and encoded to a 2D matrix where 1 means land. And 0 means water. 
How many islands are there?

*/

// It is safe to assume the input will be an array of arrays and that the values are always 0, 1
// It is worth noting that every 1 does not mean an individual island. 1's can connect to form a single landmass

/*
{{1, 1, 0, 0, 0},
 {0, 1, 0, 0, 1},
 {1, 0, 0, 1, 1},
 {0, 0, 0, 0, 0},
 {1, 0, 1, 0, 1}}
 */
 
 function mapIsland(arr) {
  let landHash = {};
  let landCount = 0;
  let queue = [];

  for (let i = 0; i < arr.length; i++) {
    for (let j = 0; j < arr[i].length; j++) {
      if (arr[i][j] === 1) {
        if (!checkMap(i + '-' + j)) {
          walkLand([i, j]);
          landCount++;
        }
      }
    }
  }

  function checkMap(index) {
    if (landHash[index]) {
      return true;
    }

    return false;
  }

  function walkLand(pair) {
    let i = pair[0];
    let j = pair[1];

    landHash[i + '-' + j] = 1;
    console.log(landHash);

    if (!(j === arr.length - 1)) {
      if (arr[i][j + 1]) {
        
        queue.push([i, j + 1]);
      }
    }
    
    if (!(j === arr.length - 1) && !(i === arr.length - 1)) {
      if (arr[i + 1][j + 1]) {
          queue.push([i + 1, j + 1]);
        }
    }
    
      
      if (!(i === arr.length - 1)) {
        
        
        if (arr[i + 1][j]) {
          queue.push([i + 1, j]);
        }
        
        if (!(j === 0)) {
          if (arr[i + 1][j - 1]) {
            queue.push([i + 1, j - 1]);
          }
        }
      }
    
    
    if (queue.length) {
      walkLand(queue.shift());
    }
    else {
      return;
    }
  }



  return landCount;
}

This currently exceeds call stack size I put this up to get feedback from other communities. Working on an implementation that uses queue