Can Javascript objects be accessed like arrays?

Question

Assuming an object is initialized as following:

var myObj = {
   "key1":"val1",
   "key2":"val2",
   "key3":"val3",
   ...
};

Can I retrieve key values like this?

var retrKey1 = myObj[0];
var retrKey2 = myObj[1];
var retrKey3 = myObj[2];
...

The issue I am trying to solve is that I need to pick random key values from this object. Generating a random number is not an issue, but:

How can I retrieve the number of keys in the object/map?
Can I retrieve the key values using a integer index like in arrays?

If not, what are my options?

What happened when you tried it?

Andy
– Andy

2013-09-16 10:43:09 +00:00
Commented Sep 16, 2013 at 10:43 — Andy
– Andy, Commented Sep 16, 2013 at 10:43

Wiktor Zychla · Accepted Answer · 2013-09-16 10:50:14Z

4

The Object.keys method returns an array of object properties. You can index the array with numbers then.

var myObj = {
 "key1":"val1",
 "key2":"val2",
 "key3":"val3",
 ...
};
var keys = Object.keys(myObj);

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys

answered Sep 16, 2013 at 10:50

Wiktor Zychla

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2 Comments

Denys Séguret Over a year ago

The order isn't guaranteed. You might have different results in different engines/browsers/executions.

Mogsdad Over a year ago

Since the OP is looking for random key values, ordering and consistency between implementations is moot. Given a random x in 0..maxKey, their random property will be myObj[keys[x]]. I think that's exactly what they're asking for.

Denys Séguret · Accepted Answer · 2013-09-16 10:43:19Z

4

No, because there's no ordering among property keys. If you want ordered keys, you need to work with an array.

You could define a structure like this :

var myObj = [
    {key:"key1", val:"val1"},
    ...
];

answered Sep 16, 2013 at 10:43

Denys Séguret

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3 Comments

steo Over a year ago

He can use myobj['property'] too

Denys Séguret Over a year ago

@steo I understand from the question that OP wants to use "an integer index", not the property name.

steo Over a year ago

yeah I was not blaming you

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