Counting Occurrences of Object Values

Question

I am trying to loop through some data in a JSON file and count the number of same cities/occurrences...

var json = [
  { \"city\": \"California\" },
  { \"ci         


        

Answer 1

Nevermind, long day.

I noticed I forgot to access the property city

The Fix: obj[json[i].city]

Thanks!

Answer 2

An alternate way of phrasing this:

json.reduce(function(sums,entry){
   sums[entry.city] = (sums[entry.city] || 0) + 1;
   return sums;
},{});

Array.reduce() calls a callback on each element of the array, passing the return of the previous call in as the first parameter in the next. (The {} at the end is the initial value, passed into the first call)

So this is doing exactly what you did - creating an empty object, iterating through the array, and accumulating totals inside the object. It's just doing it tersely.