convert json to javascript object for datables

I want to convert json into a javascript object but i am unable to do so,since i am new.

{"campaigns":{"campDetails":[{"campaign_id":"1012","campaign_name":"RP - Axe Sample (Submit)"}]}}

into

"columns": [
            { "data": {} },
            { "data": "hr.position" },
            { "data": "contact.0" },
            { "data": "contact.1" },
            { "data": "hr.start_date" },
            { "data": "hr.salary" }
        ]

javascript object format