gameoflife

function gameoflife(matrix) {
  var population = [];
  for (var i = 0; i < matrix.length; i++) {
    population[i] = [];
    for (var j = 0; j < matrix[0].length; j++)
      population[i][j] = 0;
  }

  matrix.forEach(function(row, i) {
    row.forEach(function(col, j) {
      if (col) {
        if (i>0)
          population[i-1][j] += 1;
        if (i<matrix.length-1)
          population[i+1][j] +=1;
        if (j>0)
          population[i][j-1] += 1;
        if (j<matrix[0].length-1)
          population[i][j+1] += 1;
      }
    });
  });

  population.forEach(function(row, i) {
    row.forEach(function(col, j) {
      matrix[i][j] = col > 1 && col < 4 ? true : false;
    });
  });

  return matrix;
}