基于给定键将对象数组转换为对象

Question

I am new to Javascript.

I need to write a function to covert an array of objects to an object with a given key.

The input is like this

convert([{id: 1, value: 'abc'}, {id: 2, value: 'xyz'}], 'id')

and output needs to be like this

{
    '1': {id: 1, value: 'abc'},
    '2': {id: 2, value: 'xyz'}
}

I have tried the below code.

When I am trying this directly in console it seems it is working.

 var arr = [{ id: 1, name: 'John', role: 'Developer'}, { id: 2, name: 'Jane', role: 'Lead'}, { id: 3, name: 'Robbie', role: 'QA'}]; let res = arr.reduce((prev, current) => { prev[current.v] = current; return prev; }, {}) console.log(res) 

But, when I am trying do it from the function it is not working.

function f(k, v) {
  //console.log(k);              
  k.reduce((prev, current) => {
    prev[current.v] = current;
    return prev;
    console.log(prev)
  }, {})
}

f(arr, 'role');

Any help will be highly appreciated.

Answer 1

You could take a dunctional approach by mapping an assigning new object.

 function convert(array, key) { return Object.assign(...array.map(o => ({ [o[key]]: o }))); } console.log(convert([{ id: 1, value: 'abc' }, { id: 2, value: 'xyz' }], 'id')) 

Answer 2

This solution works for me:

function convert(obj, key) {
    var newObj = {};
    obj.forEach(element => {
        newObj[element[key]] = element;
    });
    return newObj;
}

var newObj = convert([{id: 1, value: 'abc'}, {id: 2, value: 'xyz'}], 'id');

console.log(newObj);

Answer 3

You're close, but you need nested bracket notation to get to the proper key name, eg

prev[current[v]]

or

a[item[keyName]] // as in code below

 const convert = (arr, keyName) => arr.reduce((a, item) => { a[item[keyName]] = item; return a; }, {}); console.log( convert([{id: 1, value: 'abc'}, {id: 2, value: 'xyz'}], 'id') ); 

Answer 4

Its simple. Why complicating by reduce and etc.,

 function convert(arr, key) { output = {}; arr.forEach(function(item) { output[item[key]] = item; }) console.log(output) return output } convert([{id: 1, value: 'abc'}, {id: 2, value: 'xyz'}], 'id') 

https://jsfiddle.net/cvydtL7p/

Answer 5

Your code is pretty much working, the only errors are to use bracket notation to access a variable key; for example:

obj[v] will evaluate to obj.id if v was id

The other error is that you are simply missing to return from your function, resulting in an undefined result

 var arr = [{ id: 1, name: 'John', role: 'Developer'}, { id: 2, name: 'Jane', role: 'Lead'}, { id: 3, name: 'Robbie', role: 'QA'}]; function f(k, v) { //console.log(k); return k.reduce((prev, current) => { prev[current[v]] = current; return prev; }, {}) } console.log(f(arr, 'role')); 

Also note that nothing after return will happen, so the console.log line in your reducer should be before that, otherwise it's ignored.

Answer 6

You can use reduce and spread like this:

 var arr = [{id: 1, value: 'abc'}, {id: 2, value: 'xyz'}]; const res = arr.reduce((total, curr) => { return {...total, [curr.id]: curr }; }, {}); console.log(res); 

refs: reduce Spread syntax