upload

src/reduce.js

+var _ = require("lodash");
+var arr = [
+  { name: 'A', a: 1, b: 2 },
+  { name: 'A', a: 2, b: 3 },
+  { name: 'B', a: 1, b: 2 },
+  { name: 'C', a: 4, b: 5 },
+  { name: 'C', a: 5, b: 6 },
+  { name: 'C', a: 1, b: 1 },
+  { name: 'D', a: 7, b: 8 }
+];
+
+var r = _.chain(arr).reduce(function(prev, curr){
+  if (_.has(prev, curr.name)) {
+    var temp = prev[curr.name];
+    temp.a = temp.a + curr.a;
+    temp.b = temp.b + curr.b;
+  } else {
+    prev[curr.name] = curr;
+  }
+  return prev;
+}, {}).value();
+
+print(JSON.stringify(r, null, '  '));
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