可以像数组一样访问Javascript对象吗？

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:

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

If not, what are my options?

Answer 1

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"},
    ...
];

Answer 2

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