How can i filter and modify each object in array in javascript?

Question

I'm developing a little webapp which receives an array of objects from an api and then shows the result on the page after adding some data to each object and deleting other objects.

I have tried by chechink if the current index element is the same as the nexts but for some reason it doesn't work.

const initialArray = [
{ x: 'one', y: 'place1'},
{ x: 'one', y: 'place1'},
{ x: 'two', y: 'place2'},
{ x: 'three', y: 'place3'},
{ x: 'three', y: 'place3'},
{ x: 'three', y: 'place3'},
{ x: 'four', y: 'place4'}
]

The expected result should be:

let resArray = [
{ x: 'one' , y: 'place1', count: 2},
{ x: 'two', y: 'place2', count: 1 },
{ x: 'three', y: 'place3', count: 3 },
{ x: 'four', y: 'place4', count: 1 }
]

console doesn't give any error so it means my algorithm was incorrect. Thanks for the support

please provide also the actual code

Axel M
– Axel M

2019-06-22 10:28:05 +00:00
Commented Jun 22, 2019 at 10:28 — Axel M
– Axel M, Commented Jun 22, 2019 at 10:28

Maheer Ali · Accepted Answer · 2019-06-22 10:30:09Z

2

You can use reduce()

const initialArray = [
  { x: 'one', y: 'place1'},
  { x: 'one', y: 'place1'},
  { x: 'two', y: 'place2'},
  { x: 'three', y: 'place3'},
  { x: 'three', y: 'place3'},
  { x: 'three', y: 'place3'},
  { x: 'four', y: 'place4'}
];

const res = initialArray.reduce((ac,{x,y}) => {
  let k = `${x}_${y}`
  if(!ac[k]) ac[k] = {x,y,count:0};
  ac[k].count++;
  return ac;


},{})
console.log(Object.values(res))

answered Jun 22, 2019 at 10:30

Maheer Ali

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