I am having an object that has the following structure

const arr = [
  {field: "f1", values: [{ count:1, value: "a"}, { count:2, value: "b"}] },
  {field: "f2", values: [{ count:3, value: "c"}, { count:4, value: "d"}] }
];

Output should look like

output = {
             f1: { name: "f1", selected: [] },
             f2: { name: "f2", selected: [] }
          }

Basically the value in field should be key in the new object, also its name should have the same value with empty selected array

Code that I tried.

arr.map(item => { 
                 return {
                     item: {name: item, selected: []
                 }
       );

CodePudding user response：

const arr = [
    { field: "f1", values: [{ count: 1, value: "a" }, { count: 2, value: "b" }] },
    { field: "f2", values: [{ count: 3, value: "c" }, { count: 4, value: "d" }] }
]

const output = arr.reduce((p, { field }) => {
    p[field] = { name: field, selected: [] };
    return p;
}, {});

console.log(output);

CodePudding user response：

We can use Array.reduce() to do it

let arr = [
    { field: "f1", values: [{ count: 1, value: "a" }, { count: 2, value: "b" }] },
    { field: "f2", values: [{ count: 3, value: "c" }, { count: 4, value: "d" }] }
]

let result = arr.reduce((a,v) => {
  let obj = {'name':v.field, 'selected': []}
  a[v.field] = obj 
  return a
},{})
console.log(result)

CodePudding user response：

Reduce saves an assignment but makes the code more complex to read.

forEach is better in this case

const arr = [
  {field: "f1", values: [{ count:1, value: "a"}, { count:2, value: "b"}]},
  {field: "f2", values: [{ count:3, value: "c"}, { count:4, value: "d"}]}
];
const obj = {}; 
arr.forEach(({field}) => obj[field] = {name:field, selected:[]})

console.log(obj)

CodePudding user response：

You can use a .map() to get the field name, and a .reduce() to compose the object from the field name:

const input = [
  {field: "f1", values: [{ count:1, value: "a"}, { count:2, value: "b"}] },
  {field: "f2", values: [{ count:3, value: "c"}, { count:4, value: "d"}] }
];

let result = input.map(obj => obj.field).reduce((acc, name) => {
  acc[name] = { name: name, selected: [] };
  return acc;
}, {});
console.log(result);

CodePudding user response：

All the other answers seem to be using reduce. Here's another way without it:

let arr = [ 
    {field: "f1", values: [{ count:1, value: "a"}, { count:2, value: "b"}]},
    {field: "f2", values: [{ count:3, value: "c"}, { count:4, value: "d"}]}
];

let newobj = {};
arr.forEach((obj) => {
    newobj[obj.field] = { name: obj.field, selected: [] }
});