Getting the .length of a object literal

Question

How can I get the "lenght" of "enemies"? I have tried many ways, but I haven´t been able to do it. I want to use the number to loop thru the enemies. I tried Object.key() and many variations, but I don't quiet get how to implemente it, or if I am going on the right direction.

var rooms = {
"start": {
    "description": "You are in a dark, cold place and you see a light to <b>north</b>\
 and you hear the sound of running water to the <b>west</b>",
    "directions": {
        "north": "clearing1",
        "west": "bridge1"
    },
    "enemies": {
      "enemy1": "enemiesDB[0]",
      "enemy2": "enemiesDB[1]"
    }
}

}

UPDATE I change the code to be an array which solved the problem.

    var rooms = {
"start": {
    "description": "You are in a dark, cold place and you see a light to <b>north</b>\
 and you hear the sound of running water to the <b>west</b>",
    "directions": {
        "north": "clearing1",
        "west": "bridge1"
    },
    "enemies": [enemiesDB[0], enemiesDB[1]]
}

Then I was able to use it in a loop like this...

rooms.start.enemies.length

Thanks @NickCordova!

What do you want "length" to mean? There's no native "length" for plain objects. — Pointy, Oct 23 '17 at 18:15
What you are asking for is a duplicate of [How to efficiently count the number of keys/properties of an object in JavaScript?](https://stackoverflow.com/q/126100/218196), but what you actually want to do is a duplicate of [Iterate through object properties](https://stackoverflow.com/q/8312459/218196). Getting the number of properties won't really help you to iterate over them. — Felix Kling, Oct 23 '17 at 18:16
I just want to get the number of values contain in "enemies" so I can run a for loop and print the names. — Chris Luna, Oct 23 '17 at 18:17
@Chris: Iterating over properties doesn't require getting the number of properties. See the duplicate. — Felix Kling, Oct 23 '17 at 18:19
"enemies[0]" is referencing an object in another array like "enemies = [skeleys, troll, mummy]" — Chris Luna, Oct 23 '17 at 18:20
You'd be better for keeping "enemies" an array so that you can use the built-in array methods. enemies : [ enemiesDB[0], enemiesDB[1] ] — Nick Cordova, Oct 23 '17 at 18:28

score 3 · Answer 1 · answered Oct 23 '17 at 18:15

3

Objects doesn't have a length, however you can use Object.keys to get an array of the enumerable own keys of an object, and read the length of that array.

answered Oct 23 '17 at 18:15

I think this is what I am looking for, but how do I implement it? – Chris Luna Oct 23 '17 at 18:16
Object.keys(rooms.start.enemies).length – Oct 23 '17 at 18:17

score 2 · Answer 2 · answered Oct 23 '17 at 18:16

2

Enemies is an object which does not have a length, i guess you want

Object.keys(rooms.start.enemies).length;

DEMO

var rooms = {
  "start": {
    "description": "You are in a dark, cold place and you see a light  and you hear the sound of running water to the <b>west</b>",
    "directions": {
      "north": "clearing1",
      "west": "bridge1"
    },
    "enemies": {
      "enemy1": "enemiesDB[0]",
      "enemy2": "enemiesDB[1]"
    }
  }
};
console.log(Object.keys(rooms.start.enemies).length);

answered Oct 23 '17 at 18:16

Sajeetharan

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I get this error when implementing the code...my code "$('#game-text').append(Object.keys(rooms.start.enemie).length);" the error "caught TypeError: Cannot convert undefined or null to object" – Chris Luna Oct 23 '17 at 18:27
which line throws the error – Sajeetharan Oct 23 '17 at 18:29
you are missing an s in enemie – Oct 23 '17 at 18:46

Getting the .length of a object literal

2 Answers2