Object sum/join nodes

[lindm]

I have the following object:

   var data={
   'ID1':{ 
   field1: 'selector1',
   field2: 'Text',
   field3: 'Text1'
   }, 
   'ID2':{ 
   field1: 'selector1',
   field2: 'Text',
   field3: 'Text2'
   },
   'ID3':{ 
   field1: 'selector2',
   field2: 'Text',
   field3: 'Text3'
   },
   'ID4':{ 
   field1: 'selector2',
   field2: 'Text',
   field3: 'Text4'
   }
   };

 

How would I sum/join all the field3 nodes for each unique field1 node? So for instance the sum/join of selector1 would be "Text1Text2" and for selector2 "Text3Text4".

 

Thanks