Thanks @jan_blaha .
There is nothing wrong with script approach. I was just confirming.

Oops. This is kind of confusing.
Scripts is the only way of grouping and aggregating data. Right?

Is there any extension available which do such tasks like grouping and aggregation?
Is there any examples available for these functions:
https://www.jsreports.com/docs/functions/#aggregates

I want to generate a report with grouping on particular fields.
e.g.
I have following data:
[{
id: 1,
message: "hello"
},
{
id: 2,
message: "hello"
},
{
id: 3,
message: "test"
}
]

Now, I want to group on the basis of message. Output should be something like this:

Message Sum
hello 2
test 1