Practicing 2D Arrays

Question

I'm writing a script that will generate a square room within a larger map. The code looks like this:

var mapSize = 10;
var map = [];
for (var x = 0; x < mapSize; x++) {
    map[x] = [];
    for (var y = 0; y < mapSize; y++) {
        map[x][y] = 0
        };
    };
//Make square room within map
var roomSize = 3;
var roomType = "Kitchen"
var paintRoom = function(mapX, mapY) {
    for (var j = 0; j < roomSize; j++) {
      map[mapX + j][mapY] = roomType;
      map[mapX][mapY + j] = roomType;
    };
};
paintRoom(3, 4);
console.log(map);

The result that I want is this:

[
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, "Kitchen", "Kitchen", "Kitchen", 0, 0, 0], 
  [0, 0, 0, 0, "Kitchen", "Kitchen", "Kitchen", 0, 0, 0], 
  [0, 0, 0, 0, "Kitchen", "Kitchen", "Kitchen", 0, 0, 0], 
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
]

But instead I end up with this:

[
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, "Kitchen", "Kitchen", "Kitchen", 0, 0, 0], 
  [0, 0, 0, 0, "Kitchen", 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, "Kitchen", 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], 
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
]

What am I missing here? I'm just starting out, and would like to figure out as much as possible on my own, so if anyone could give me a hint instead of answering outright, I would really appreciate it.

@janje They can be Brian and Hilary - it doesn't really matter for the sake of example code. — Reinstate Monica Cellio, Apr 27 '16 at 16:46
That is true, but I'm not sure renaming them would solve the problem. Or would it? — LucienLachance, Apr 27 '16 at 16:46
@LucienLachance no, it wouldn't. I've given an answer below and explained what was wrong. — Reinstate Monica Cellio, Apr 27 '16 at 16:47
What is it with the innocuous comments today? @NinaScholz that's actually really good practice and it will never be a problem, whereas leaving them out could very easily be. — Reinstate Monica Cellio, Apr 27 '16 at 16:48
@LucienLachance Perhaps, but naming things counter-intuitively can't be a good practice. — pishpish, Apr 27 '16 at 16:51
@Archer, [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block) states "*Note that the block statement does not end with a semicolon.*", but inserting does not harm;;;;;;;; :) — Nina Scholz, Apr 27 '16 at 16:55
@NinaScholz You can put a million semi-colons on a line if you want. It's a terminator and has NO side-effects. That link you gave shows a page that says a particular example _"does not end with a semicolon"_, but in no way suggests that it SHOULD not. Try this instead... http://stackoverflow.com/questions/444080/do-you-recommend-using-semicolons-after-every-statement-in-javascript — Reinstate Monica Cellio, Apr 27 '16 at 16:58

score 2 · Accepted Answer · answered Apr 27 '16 at 16:45

It is doing what you've asked, if you follow the code carefully. It just needs an extra loop. Since what you're doing is 2 dimensional then you'll need 2 loops as well...

var paintRoom = function(mapX, mapY) {
    for (var x = 0; x < roomSize; x++) {
        for (var y = 0; y < roomSize; y++) {
            map[mapX + x][mapY + y] = roomType;
        }
    };
};

score 0 · Answer 2 · answered Apr 27 '16 at 16:48

you a missing 1 loop:

var mapSize = 10;
var map = [];
for (var x = 0; x < mapSize; x++) {
    map[x] = [];
    for (var y = 0; y < mapSize; y++) {
        map[x][y] = 0
        };
    };
//Make square room within map
var roomSize = 3;
var roomType = "Kitchen"
var paintRoom = function(mapX, mapY) {
    for (var j = 0; j < roomSize; j++) {
      for (var k = 0; k < roomSize; k++) {
         map[mapX + j][mapY + k] = roomType;
      }
    };
};
paintRoom(3, 4);
console.log(map);

https://jsfiddle.net/nfnpesmd/

Practicing 2D Arrays

2 Answers2