js array of objects to object by a key code example

Example 1: javascript array to object with keys

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

Example 2: js array to object with keys

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