如何将数组转换为 object

Question

I'm trying to filter an array of objects of people into a new object with its property names arranged by age each in a separate array.

Example 1

Input:

groupAdultsByAgeRange([{name: "Henry", age: 9}, {name: "John", age: 20}])

Result:

{ '20 and younger': [ { name: 'John', age: 20 } ] }

Example 2

Input:

groupAdultsByAgeRange([{name: "Anna", age: 31}, {name: "John", age: 32}, {name: "Hank", age: 60}])

Result:

{ 
  '31-40': [ { name: 'Anna', age: 31 }, { name: 'John', age: 32 } ],
  '51 and older': [ { name: 'Hank', age: 60 } ] 
}

If the age range is not in the input than it should not be part of the output. For example if the input does not have people with age 51 than the object should not contain property of '51 and older'. and if input us empty array than output should be an empty object.

Answer 1

Using lodash you can do something like this

const _ = require('lodash');

const array = [{name: "Anna", age: 31}, {name: "John", age: 32}, {name: "Hank", age: 60}];

function ageToRange(obj) {
  const age = obj.age;
  if (age <= 20) {
    return '20 and younger';
  } 
  if (age > 30 && age <= 40) {
    return '31-40'
  }
  if (age > 50) {
    return '51 and older';
  }
}

const result = _.groupBy(array, ageToRange)

console.log(result);

Answer 2

This is how you do with native Javascript:

 //example 1 let people1 = [{name: "Henry", age: 9}, {name: "John", age: 20}] let younger_and_equal_20 = [] people1.forEach(e => { if(e.age>=20){ younger_and_equal_20.push(e) } }); console.log({"20 and younger": younger_and_equal_20}) //example 2 let people2 = [{name: "Anna", age: 31}, {name: "John", age: 32}, {name: "Hank", age: 60}] let data = { "31-40": [], "51 and older": [] } people2.forEach(e => { if(e.age>30 && e.age<=40){ data["31-40"].push(e) } else if(e.age>50){ data["51 and older"].push(e) } }); console.log(data)

Answer 3

    let result = {}

    function groupAdultsByAgeRange(people) {
        // An array of object which represents people who are 20 or younger
        const ageGroup = people.filter(person => person.age <= 20)

        // Only add array to the object key if it's not empty
        if (ageGroup.length > 0) {
            result["20 and younger"] = ageGroup
        }

        return result;
    }