index.js

var _ = require('underscore');

module.exports = function() {
  var board, length, width;
  var top = left = function(n) {
    var z = n - 1;
    return z < 0 ? null : z;   
  };
  var bottom = function(n) {
    var z = n + 1;
    return z >= width ? null : z;  
  };
  var right = function(n) {
    var z = n + 1;
    return z >= length ? null : z;  
  };
  var middle = center = function(n) { return n; };
  var isAlive = function(x,y) {
    if(_.isNumber(x) && _.isNumber(y)) {
      return board[x][y];  
    }  
    else {
      return false;
    } 
  };
  var combine = function(x,y) {
    return _.partial(isAlive, x, y, board);
  };
  //initializes array with false
  var init = function(x ,y) { 
    var b = _.times(x, function(){
      return _.times(y, function() {
        return false;
      });
    });
    return b;  
  };
  var create = function(b) {
    _.each(b, function(row, i) {
      _.each(row, function(val, j) {
        b[i][j] = _.random(1) === 1 ? true : false;
      });
    });
  };
  var getNeighbors = function(x,y,b) {
    length = b[0].length;
    width = b.length;
    board = b;

    var topLeft = combine(top(x), left(y));
    var topMiddle = combine(top(x), middle(y));
    var topRight = combine(top(x), right(y));
    var centerLeft = combine(center(x), left(y));
    var centerRight = combine(center(x), right(y));
    var bottomLeft = combine(bottom(x), left(y));
    var bottomMiddle = combine(bottom(x), middle(y));
    var bottomRight = combine(bottom(x), right(y));

    var neighbors = [
      topLeft(),
      topMiddle(),
      topRight(),
      centerLeft(),
      centerRight(),
      bottomLeft(),
      bottomMiddle(),
      bottomRight()
    ];

    //console.log(neighbors);
    var alive = _.without(neighbors, false);      
    return alive.length;   
  };
  var calculateLife = function(alive,x,y,b) {
    if(alive) {
      return (getNeighbors(x,y,b) < 2 || getNeighbors(x,y,b) > 3) ? false : true; 
    } 
    else {
      return getNeighbors(x,y,b) === 3 ? true : false;
    }  
  };
  return {
    seed: function(x,y) {
      var b = init(x,y);
      create(b);
      //console.log(b);
      return b;  
    },
    tick: function(b) {
     return _.map(b, function(row,x) {
        return _.map(row, function(alive,y) {
          return calculateLife(alive,x,y,b);  
        });
      }); 
      //console.log(next);
      //return next;
    },
  };
};