1let arr = [{a: 'a', b: 1, c: 'c'}, {a: 'a', b: 2, c: 'c'}, {a: 'a', b: 3, c: 'c'}]:
2 let mapped = arr.reduce (function (map, obj) { 
3        map[obj.b] = obj; 
4        return map;
5      },{}); // reduce
6console.log (mapped); // {1: {a: 'a', b: 1, c: 'c'}, 2: {a: 'a', b: 2, c: 'c'}, 3: {a: 'a', b: 3, c: 'c'}

1const arr = ['a','b','c'];
2const res = arr.reduce((a,b)=> (a[b]='',a),{});
3console.log(res)

1const subLocationTypes = (location.subLocationTypes || []).reduce((add, cur) => {
2add[cur.key] = cur.value;
3return add;
4}, {});