Sum values in JSON array response

Question

I have a JSON string from an API response which looks like this:

{ "legend_size": 1,
  "data": {
    "series": [ "2013-05-01", "2013-05-02" ],
    "values": {
        "Sign Up": {
            "2013-05-05": 10,
            "2013-05-04": 10
         }
     }
  }
}

I'd like to sum the values in the "Sign Up" Object (10 + 10). The challenge I am having is that the key's are unique and most of the posts demonstrating how to do something like this show examples where it is just an array of values or the keys are consistent (ie - every key is "value").

Should I be attempting to use the Series array to loop through the Sign Up Object?

forgot to mention, my first step in trying to solve this was to use JSON.parse(string); to put it in to a JS Object. Not sure if that is necessary. — nielsfogt
– nielsfogt, Commented Jun 10, 2013 at 1:53

jcsanyi · Accepted Answer · 2013-06-10 02:01:35Z

4

Assuming you've already got your data parsed into an object, you can use a for loop like this:

var json = {
    "legend_size": 1,
    "data": {
        "series": [ "2013-05-01", "2013-05-02" ],
        "values": {
            "Sign Up": {
                "2013-05-05": 10,
                "2013-05-04": 10
            }
        }
    }
};
var sum = 0;
for (x in json.data.values['Sign Up']) {
    sum += json.data.values['Sign Up'][x];
}

Basically, we navigate through the json data to get the the actual data that we want... which is the 'Sign Up' object. Then we use a for/in loop to loop through all the keys that that object has, and add up the values.

edited Jun 10, 2013 at 2:01

answered Jun 10, 2013 at 1:56

jcsanyi

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Comments

user2437417 · Accepted Answer · 2013-06-10 02:00:03Z

0

After you've parsed it, here's a way to arrive at the sum by using Array.prototype.reduce.

var vals = object.data.values["Sign Up"];

var result = Object.keys(vals)
                   .reduce(function(sum, key) {
                       return sum + vals[key]
                   }, 0);

The .reduce() and .keys() methods will need shims for IE8 and lower.

answered Jun 10, 2013 at 2:00

user2437417

2 Comments

nielsfogt Over a year ago

This works as well :) Thanks so much...any reason why this solution vs. @jcsanyi's would be any better/worse?

user2437417 Over a year ago

Just different approaches to the same problem. This one uses a functional approach, and is probably a little slower, but would only manifest itself on very large sets of data.

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