Modify JavaScript code to use higher order functions

Question

My below code is working fine and gives the correct desired output. But I am trying to use map, filter etc. instead of for loop. Lodash map and filter also works.

var arr = [
  {"comp_id":1, desc: 'from comp1', updated: true},
{
"comp_id":2, desc: 'from comp2', updated: false}
  ];

  var complaint_sources = [
    {"comp_id":2,"consumer_source":"Hotline In","description_option":"English"},
    {"comp_id":1,"consumer_source":"Online","description_option":"Other"},
    {"comp_id":1,"consumer_source":"Email","description_option":null},
    {"comp_id":2,"consumer_source":"Email","description_option":null}]

  for(let i =0 ;i<arr.length;i++) {
    let x=[];
    for(let j=0;j<complaint_sources.length;j++){
      if(arr[i].comp_id === complaint_sources[j].comp_id){
        x.push(complaint_sources[j]);
        arr[i].comp_src = x;
      }
    }
  }
  console.log(arr);

Basically I am looping through arr array and inside that looping through the complaint_sources array and when the comp_id matches I am modifying the arr array and adding a comp_src property to the object of arr array. This comp_src property will be an array of complaint_sources matched by comp_id.

Since the code works you could always try codereview.stackexchange.com — imvain2
– imvain2, Commented Aug 18, 2020 at 18:48
Maybe it's easier to see how to do this when you move the arr[i].comp_src = x; out of the inner for loop (so that actually each arr[i] gets a .comp_src, even when it's the empty array). — Bergi
– Bergi, Commented Aug 18, 2020 at 20:36

TheWuif · Accepted Answer · 2020-08-18 20:12:22Z

1

this will work:

var arr = [
  {"comp_id":1, desc: 'from comp1', updated: true},
  {"comp_id":2, desc: 'from comp2', updated: false}
];

var complaint_sources = [
  {"comp_id":2,"consumer_source":"Hotline In","description_option":"English"},
  {"comp_id":1,"consumer_source":"Online","description_option":"Other"},
  {"comp_id":1,"consumer_source":"Email","description_option":null},
  {"comp_id":2,"consumer_source":"Email","description_option":null}
];
  
const grouped_sources = complaint_sources.reduce((acc, value) => {
  (acc[value.comp_id] = acc[value.comp_id] || []).push(value);
  return acc;
}, {})
  
const data = arr.map((comp) => ({
  ...comp,
  comp_src: grouped_sources[comp.comp_id]
}));

console.log(data);

edited Aug 18, 2020 at 20:12

answered Aug 18, 2020 at 19:09

TheWuif

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