javascript - Looking for the most elegant way to process data?

Question

Given the endorsement array, it is required to write a function to achieve the desired output result:

// function input 
var endorsements = [ 
{ skill: 'javascript', user: 'Chad' }, 
{ skill: 'javascript', user: 'Bill' }, 
{ skill: 'javascript', user: 'Sue' }, 
{ skill: 'html', user: 'Sue' }, 
{ skill: 'css', user: 'Sue' }, 
{ skill: 'css', user: 'Bill' } 
]; 

// function output 
[ 
{ skill: 'javascript', user: [ 'Chad', 'Bill', 'Sue' ], count: 3 }, 
{ skill: 'css', user: [ 'Sue', 'Bill' ], count: 2 }, 
{ skill: 'html', user: [ 'Sue' ], count: 1 } 
];

Answer 1

let output = []

endorsements.reduce((dict, item) => {
  if (!dict[item.skill]) {
    dict[item.skill] = {
      skill: item.skill,
      user: [item.user],
      count: 1
    }
    output.push(dict[item.skill])
  } else {
    dict[item.skill].user.push(item.user)
    dict[item.skill].count += 1
  }
  return dict
}, {})

output = output.sort((a, b) => b.count - a.count)

console.log(output)