Group by without Ramda

group-by-without-ramda.js

const data = [
  {
    category: 'action',
    value: 'jorgs'
  },
   {
    category: 'comedy',
    value: 'lucians'
  },
   {
    category: 'action',
    value: 'pedrs'
  },
   {
    category: 'drama',
    value: 'lucs'
  },
]

const prop = name => obj => obj[name]

const groupBy = grouper => list => list.reduce((acc, curr) => ({
    ...acc,
    [grouper(curr)]: [curr, ...(acc[grouper(curr)] || [])],
}), {})

groupBy(prop('category'))(data)

// {
//     action: [
//         {
//             category: "action",
//             value: "jorgs"
//         },
//         {
//             category: "action",
//             value: "pedrs"
//         }
//     ],
//     comedy: [
//         {
//             category: "comedy",
//             value: "lucians"
//         }
//     ],
//     drama: [
//         {
//             category: "drama",
//             value: "lucs"
//         }
//     ]
// }