js json groupby prop

function groupArrayOfObjects(list, key) {
  return list.reduce(function(rv, x) {
    (rv[x[key]] = rv[x[key]] || []).push(x);
    return rv;
  }, {});
};

var people = [
    {sex:"Male", name:"Jeff"},
    {sex:"Female", name:"Megan"},
    {sex:"Male", name:"Taylor"},
    {sex:"Female", name:"Madison"}
];
var groupedPeople=groupArrayOfObjects(people,"sex");
console.log(groupedPeople.Male);//will be the Males 
console.log(groupedPeople.Female);//will be the Femalesvar myJsonFromSQL = [{id:1, cat:'test1'},{id:2, cat:'test1'},
                     {id:3, cat:'test2'},{id:4, cat:'test2'}];

// 1 LINE CODE:
//'Set' deletes/do not consider duplicates
const arr_cat =  [...new Set(myJsonFromSQL.map(i => i.cat))];
//RESULT:
You will get an array with the property values grouped:
arr_cat   ['test1','test2']