Read and loop through an object with non-unique key value pairs

Question

I have an object which contains some key/value pairs. When there is a key/value pair that shares the same key as another key/value pair, the first one is not recognised when I console log the object.

For example:

var test = {
"same" : 'Value1',
"same" : 'Value2',
"different" : 'Value3'
};
console.log(test);

Results in the console as:

Object { same="Value2", different="Value3"}

Is it not possible to read an object that has similar key names?

I am trying to loop through the object using this method (How do I loop through or enumerate a JavaScript object?) but I can only ever retrieve one the key/value pairs that share a key.

score 2 · Answer 1 · answered Jul 05 '13 at 08:12

2

An object can not have duplicate keys.

So the reason that you can't read the duplicate keys from the object, is that they were never added as two items in the object in the first place. One of the items will simply overwrite the other.

answered Jul 05 '13 at 08:12

Guffa

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score 1 · Accepted Answer · answered Jul 05 '13 at 08:12

1

Could you change the structure of the JSON if needed? JSON objects cannot have duplicate keys. Think of it as a hashmap or dictionary. Depending on the language and JSON parser you may also get an exception (not in Javascript though)

In your example above either change it so that you have unique keys or change ti to an array of values like:

var test = {
"same" : ['Value1', 'Value2']
"different" : 'Value3'
};
console.log(test);

answered Jul 05 '13 at 08:12

Yannis

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2

Or change it to an array of key/value: [{"same" : 'Value1'}, {"same" : 'Value2'}, {"different" : 'Value3'}]. It's like in most langages: object is similar to a set, and a set cannot contain 2 equal objects. So use a list instead :D – Ricola3D Jul 05 '13 at 08:48
@Yannis thanks for that suggestion, that will work for my purposes. – Dave Haigh Jul 05 '13 at 09:03
Glad I could help. Wouldnt mind if you accepted the answer since you found it useful :) – Yannis Jul 05 '13 at 09:04

score 0 · Answer 3 · answered Jul 05 '13 at 08:11

0

A key is a unique value that uniquely identifies the element within the array/object. So, the answer is no, you can't have two elements with the same key value.

answered Jul 05 '13 at 08:11

RST

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Read and loop through an object with non-unique key value pairs

3 Answers3

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