JAVASCRIPT

lodash groupBy

Creates an object composed of keys generated from the results of running 
each element of collection thru iteratee. The order of grouped values is 
determined by the order they occur in collection. The corresponding value 
of each key is an array of elements responsible for generating the key. 
The iteratee is invoked with one argument: (value).

_.groupBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': [4.2], '6': [6.1, 6.3] }
 
// The `_.property` iteratee shorthand.
_.groupBy(['one', 'two', 'three'], 'length');
// => { '3': ['one', 'two'], '5': ['three'] }

lodash groupby return array

export const groupArrayBy = (arr, groupBy) => {

    let newArr = []
    arr.map((item) => {
        if(item[groupBy]) {
            let finded = newArr.filter((newItem) => newItem[groupBy] === item[groupBy])
            if(finded.length > 0) {
                finded[0].products.push(item)
            } else {
                newArr.push({category: item[groupBy], products: [item]})
            }
        }
    })

    return newArr
}

lodash groupby return array

   let arr = [{
	"birthdate": "1993",
	"name": "Ben"
},
{
	"birthdate": "1994",
	"name": "John"
},
{
	"birthdate": "1995",
	"name": "Larry"
},
{
	"birthdate": "1995",
	"name": "Nicole"
},
{
	"birthdate": "1996",
	"name": "Jane"
},
{
	"birthdate": "1996",
	"name": "Janet"
},
{
	"birthdate": "1996",
	"name": "Dora"
},
];

const res = arr.reduce((ac, a) => {
let temp = ac.find(x => x.birthdate === a.birthdate);
if (!temp) ac.push({ ...a,
	name: [a.name]
})
else temp.name.push(a.name)
return ac;
}, [])
console.log(res);

lodash groupby with map

var result = _.chain(mockData)
      .groupBy(function(item) {
        return moment(item.start_date.substring(0,10)).format("MMM-DD-YYYY"); 
      })
      .map((value, key) => {
        return {
          date: key, 
          param: value
        }
      })
      .value();

lodash groupby return array

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