A tiny library to group array of objects based on multiple properties.
Ultra small, just 0.3KB [minified+gzipped] and 1.38KB [uncompressed source].

If you are using npm

$ npm install --save group-object-array

or include index.js manually as

<script src="index.js" charset="utf-8"></script>

const groupBy = require('group-object-array');

var result = groupBy([{"a":1,"b":{"c":"C"}},{"a":2,"b":{"c":"D"}},{"a":1,"b":{"c":"C"}},{"a":1,"b":{"c":"A"}}], 'a');
          or groupBy(test, ['a', 'b.c']);
//groupBy(test, ['a', 'b.c']) returns
[{"key":"1","children":[{"key":"C","children":[{"a":1,"b":{"c":"C"}},{"a":1,"b":{"c":"C"}}]},{"key":"A","children":[{"a":1,"b":{"c":"A"}}]}]},{"key":"2","children":[{"key":"D","children":[{"a":2,"b":{"c":"D"}}]}]}]

For browser environments, the library exports a global arrayGroup, which can be used in a similar fashion,

arrayGroup(test, ['a', 'b.c']);
// returns the grouped 'test' array

Groups and returns an array.

Type: Array
Default: none

Array to be grouped.

Type: String | Array
Default: none

The priority order which grouping is to be performed. A single string value or array of strings.

Type: Function
Default: none

The transformation function to be applied to keys on which grouping is specified.
It is a function which accepts the object from input array and returns an array of specifying transformation for each key level.
For example,
groupBy(test, ['a', 'b.c' ...], function(item){ return [item.toString() + '~key~1', f(item.property)...] })
where f is any transformation function.
Note that transformation is applied at the output result for transforming input to a consumable output. If used, transformation must be specified for each key level.

MIT © The Half Blood Prince