How to selectively filter an array of objects using another array in JavaScript

Question

How to selectively filter an array of objects using another array in JavaScript

Imagine you have an array filled with objects:

people = [
    {id: "1", name: "abc", gender: "m", age:"15" },
    {id: "2", name: "a", gender: "m", age:"25" },
    {id: "3", name: "efg", gender: "f", age:"5" },
    {id: "4", name: "hjk", gender: "m", age:"35" },
    {id: "5", name: "ikly", gender: "m", age:"41" },
    {id: "6", name: "ert", gender: "f", age:" 30" },
    {id: "7", name: "qwe", gender: "f", age:" 31" },
    {id: "8", name: "bdd", gender: "m", age:" 78" },
]

Additionally, you also have an array containing desired ids:

id_filter = [1,4,5,8]

Your task is to filter the people array to only show the specified ids from id_filter where the gender is set to m.

javascript arrays filter array-of-dict

Answer 1

Answer №1

An easy method for sorting data is by utilizing the array's filter() function, like shown below:

users.filter(user => id_filter.includes(user.id))

Answer 2

An easy method for sorting data is by utilizing the array's filter() function, like shown below:

users.filter(user => id_filter.includes(user.id))

Answer 3

Answer №2

If you want to achieve the desired output, you can utilize array.filter() method with specific conditions. I have also made corrections to your JSON structure.

var filtered = people.filter(function(item) {
        return id_filter.indexOf(item.id) !== -1 && item.gender==='m';
});

DEMO

var  people =[
  { "id": 1, "name": "abc", "gender": "m","age": "15" },
  { "id": 2, "name": "a", "gender": "m", "age": "25"  },
  { "id": 3,"name": "efg", "gender": "f","age": "5" },
  { "id": 4,"name": "hjk","gender": "m","age": "35" },
  {  "id": 5, "name": "ikly","gender": "m","age": "41" },
  { "id": 6, "name": "ert", "gender": "f", "age": "30" },
  { "id": 7, "name": "qwe", "gender": "f", "age": "31" },
  { "id":8, "name": "bdd",  "gender": "m", "age": " 8" }
];
var id_filter = [1,4,5,8];
var filtered = people.filter(function(item) {
    return id_filter.indexOf(item.id) !== -1 && item.gender==='m';
});
console.log(filtered);

Answer 4

If you want to achieve the desired output, you can utilize array.filter() method with specific conditions. I have also made corrections to your JSON structure.

var filtered = people.filter(function(item) {
        return id_filter.indexOf(item.id) !== -1 && item.gender==='m';
});

DEMO

var  people =[
  { "id": 1, "name": "abc", "gender": "m","age": "15" },
  { "id": 2, "name": "a", "gender": "m", "age": "25"  },
  { "id": 3,"name": "efg", "gender": "f","age": "5" },
  { "id": 4,"name": "hjk","gender": "m","age": "35" },
  {  "id": 5, "name": "ikly","gender": "m","age": "41" },
  { "id": 6, "name": "ert", "gender": "f", "age": "30" },
  { "id": 7, "name": "qwe", "gender": "f", "age": "31" },
  { "id":8, "name": "bdd",  "gender": "m", "age": " 8" }
];
var id_filter = [1,4,5,8];
var filtered = people.filter(function(item) {
    return id_filter.indexOf(item.id) !== -1 && item.gender==='m';
});
console.log(filtered);

Answer 5

Answer №3

Using the Array.includes() method:

var people = [
    {id : "1", name : "abc", gender : "m", age :"15" }, {id : "2", name : "a", gender : "m", age :"25" },
    {id : "3", name : "efg", gender : "f", age :"5" },  {id : "4", name : "hjk", gender : "m", age :"35" },
    {id : "5", name : "ikly", gender : "m", age :"41" }, {id : "6", name : "ert", gender : "f", age :" 30" },
    {id : "7", name : "qwe", gender : "f", age :" 31" }, {id : "8", name : "bdd", gender : "m", age :" 78" }
], 
    id_filter = [1,4,5,8],
    result = people.filter((o) => id_filter.includes(+o.id) && o.gender == "m");       

console.log(result);

+o.id - The + symbol is used to convert a numeric string into a number

Answer 6

Using the Array.includes() method:

var people = [
    {id : "1", name : "abc", gender : "m", age :"15" }, {id : "2", name : "a", gender : "m", age :"25" },
    {id : "3", name : "efg", gender : "f", age :"5" },  {id : "4", name : "hjk", gender : "m", age :"35" },
    {id : "5", name : "ikly", gender : "m", age :"41" }, {id : "6", name : "ert", gender : "f", age :" 30" },
    {id : "7", name : "qwe", gender : "f", age :" 31" }, {id : "8", name : "bdd", gender : "m", age :" 78" }
], 
    id_filter = [1,4,5,8],
    result = people.filter((o) => id_filter.includes(+o.id) && o.gender == "m");       

console.log(result);

+o.id - The + symbol is used to convert a numeric string into a number

Answer 7

Answer №4

If you want to accomplish this, you can utilize the code snippet below:

const filtered_people = people.filter(function(person){
    return id_filter.includes(person.id) && person.gender === 'm';
});

Ensure that each person's id is an integer and not a string, as shown in your example. Otherwise, the includes() function will fail to match. Additionally, there seem to be syntax errors within your people array. Therefore, the corrected code should appear like this:

const people = [
    {id: 1, name: "abc", gender: "m", age:15},
    {id: 2, name: "a", gender: "m", age: 25},
    {id: 3, name: "efg", gender: "f", age: 5},
    {id: 4, name: "hjk", gender: "f", age: 35},
    {id: 5, name: "ikly", gender: "m", age: 41},
    {id: 6, name: "ert", gender: "f", age: 30},
    {id: 7, name: "qwe", gender: "f", age: 31},
    {id: 8, name: "bdd", gender: "m", age: 78}
]
const id_filter = [1,4,5,8]
const filtered_people = people.filter((person) => id_filter.includes(person.id) && person.gender === 'm')
console.log(filtered_people)

I trust this guidance proves beneficial. Best of luck.

Answer 8

If you want to accomplish this, you can utilize the code snippet below:

const filtered_people = people.filter(function(person){
    return id_filter.includes(person.id) && person.gender === 'm';
});

Ensure that each person's id is an integer and not a string, as shown in your example. Otherwise, the includes() function will fail to match. Additionally, there seem to be syntax errors within your people array. Therefore, the corrected code should appear like this:

const people = [
    {id: 1, name: "abc", gender: "m", age:15},
    {id: 2, name: "a", gender: "m", age: 25},
    {id: 3, name: "efg", gender: "f", age: 5},
    {id: 4, name: "hjk", gender: "f", age: 35},
    {id: 5, name: "ikly", gender: "m", age: 41},
    {id: 6, name: "ert", gender: "f", age: 30},
    {id: 7, name: "qwe", gender: "f", age: 31},
    {id: 8, name: "bdd", gender: "m", age: 78}
]
const id_filter = [1,4,5,8]
const filtered_people = people.filter((person) => id_filter.includes(person.id) && person.gender === 'm')
console.log(filtered_people)

I trust this guidance proves beneficial. Best of luck.

Answer 9

Answer №5

If you encounter this scenario, utilizing the filter and include methods can be beneficial. Remember that since your ids are in string format, they will need to be converted before being used.

var filteredResult = individuals.filter((individual) => (idList.includes(parseInt(individual.id)) && individual.gender === 'male'))

Answer 10

If you encounter this scenario, utilizing the filter and include methods can be beneficial. Remember that since your ids are in string format, they will need to be converted before being used.

var filteredResult = individuals.filter((individual) => (idList.includes(parseInt(individual.id)) && individual.gender === 'male'))

Answer 11

Answer №6

When approaching this scenario, it is more efficient to travel by foot. Start by looping through the people array, then compare each person's ID with the filter list.

for(person in people) {
     for(id in id_filter) {
         if(person[id] == id && person[gender] == "m"){

         }
     }
}

Answer 12

When approaching this scenario, it is more efficient to travel by foot. Start by looping through the people array, then compare each person's ID with the filter list.

for(person in people) {
     for(id in id_filter) {
         if(person[id] == id && person[gender] == "m"){

         }
     }
}

Answer 13

Answer №7

To apply the Array.prototype.filter method, you can utilize the following code snippet:

function filterByGender(arr, indexes, gender) {                              // this function takes an array of people arr, an array of indexes ids, and a gender to filter and return the matching people objects from arr
  return arr.filter(function(person) {                              // filters each person object...
    return indexes.includes(person.id) && person.gender === gender;        // checks if this person's id is in the provided indexes array and if their gender matches the specified one
  });
}

var individuals = [{id:"1",name:"John",gender:"m",age:25},{id:"2",name:"Jane",gender:"f",age:30},{id:"3",name:"Alex",gender:"m",age:45},{id:"4",name:"Emily",gender:"f",age:28},{id:"5",name:"Sam",gender:"m",age:33}];

console.log(filterByGender(individuals, ["1", "3", "5"], "m"));               // filters elements with ids ["1", "3", "5"] and gender "m".

Note: The id property values in the individuals array are strings so when using includes, make sure to either provide string ids or convert the id property to numbers before comparison.

Answer 14

To apply the Array.prototype.filter method, you can utilize the following code snippet:

function filterByGender(arr, indexes, gender) {                              // this function takes an array of people arr, an array of indexes ids, and a gender to filter and return the matching people objects from arr
  return arr.filter(function(person) {                              // filters each person object...
    return indexes.includes(person.id) && person.gender === gender;        // checks if this person's id is in the provided indexes array and if their gender matches the specified one
  });
}

var individuals = [{id:"1",name:"John",gender:"m",age:25},{id:"2",name:"Jane",gender:"f",age:30},{id:"3",name:"Alex",gender:"m",age:45},{id:"4",name:"Emily",gender:"f",age:28},{id:"5",name:"Sam",gender:"m",age:33}];

console.log(filterByGender(individuals, ["1", "3", "5"], "m"));               // filters elements with ids ["1", "3", "5"] and gender "m".

Note: The id property values in the individuals array are strings so when using includes, make sure to either provide string ids or convert the id property to numbers before comparison.

Answer 15

Answer №8

To optimize performance for a large id_filter, the best approach is to convert it into a new Set(). This conversion allows for constant-time lookup. Subsequently, you can utilize the .filter() method to iterate through your people array and return true if the set contains the id and the gender is 'm'.

const people = [ {id: "1", name: "abc", gender: "m", age:"15" }, {id: "2", name: "a", gender: "m", age:"25" }, {id: "3", name: "efg", gender: "f", age:"5" }, {id: "4", name: "hjk", gender: "m", age:"35" }, {id: "5", name: "ikly", gender: "m", age:"41" }, {id: "6", name: "ert", gender: "f", age:" 30" }, {id: "7", name: "qwe", gender: "f", age:" 31" }, {id: "8", name: "bdd", gender: "m", age:" 78" }, ];

const id_filter = new Set([1,4,5,8]);
const res = people.filter(({id, gender}) => id_filter.has(+id) && gender === 'm');
console.log(res);

This optimized approach results in a time complexity of O(N + k), which is far better than the O(Nk) complexity incurred by using methods like .includes() or .indexOf(). Here, N represents the length of the people array, while k represents the length of the id_filter array.

Answer 16

To optimize performance for a large id_filter, the best approach is to convert it into a new Set(). This conversion allows for constant-time lookup. Subsequently, you can utilize the .filter() method to iterate through your people array and return true if the set contains the id and the gender is 'm'.

const people = [ {id: "1", name: "abc", gender: "m", age:"15" }, {id: "2", name: "a", gender: "m", age:"25" }, {id: "3", name: "efg", gender: "f", age:"5" }, {id: "4", name: "hjk", gender: "m", age:"35" }, {id: "5", name: "ikly", gender: "m", age:"41" }, {id: "6", name: "ert", gender: "f", age:" 30" }, {id: "7", name: "qwe", gender: "f", age:" 31" }, {id: "8", name: "bdd", gender: "m", age:" 78" }, ];

const id_filter = new Set([1,4,5,8]);
const res = people.filter(({id, gender}) => id_filter.has(+id) && gender === 'm');
console.log(res);

This optimized approach results in a time complexity of O(N + k), which is far better than the O(Nk) complexity incurred by using methods like .includes() or .indexOf(). Here, N represents the length of the people array, while k represents the length of the id_filter array.

Answer 17

Answer №9

const people = [
    {id: "1", name: "abc", gender: "m", age: "15" },
    {id: "2", name: "a", gender: "m", age: "25" },
    {id: "3", name: "efg", gender: "f", age: "5" },
    {id: "4", name: "hjk", gender: "m", age: "35" },
    {id: "5", name: "ikly", gender: "m", age: "41" },
    {id: "6", name: "ert", gender: "f", age: " 30" },
    {id: "7", name: "qwe", gender: "f", age: " 31" },
    {id: "8", name: "bdd", gender: "m", age: " 78" },
]

const idFilter = [1,4,5,8]

const idIsInList = id => idFilter.includes(+id) // Ensuring it is a number, not a string
const genderIsMale = gender => gender === "m"
const result = people.filter(item => idIsInList(item.id) && genderIsMale(item.gender))

console.log(result)

Answer 18

const people = [
    {id: "1", name: "abc", gender: "m", age: "15" },
    {id: "2", name: "a", gender: "m", age: "25" },
    {id: "3", name: "efg", gender: "f", age: "5" },
    {id: "4", name: "hjk", gender: "m", age: "35" },
    {id: "5", name: "ikly", gender: "m", age: "41" },
    {id: "6", name: "ert", gender: "f", age: " 30" },
    {id: "7", name: "qwe", gender: "f", age: " 31" },
    {id: "8", name: "bdd", gender: "m", age: " 78" },
]

const idFilter = [1,4,5,8]

const idIsInList = id => idFilter.includes(+id) // Ensuring it is a number, not a string
const genderIsMale = gender => gender === "m"
const result = people.filter(item => idIsInList(item.id) && genderIsMale(item.gender))

console.log(result)

Answer 19

Answer №10

    individuals = [
        {id : "1", name : "abc", gender : "m", age :"15" },
        {id : "2", name : "a", gender : "m", age :"25" },
        {id : "3", name : "efg", gender : "f", age :"5" },
        {id : "4", name : "hjk", gender : "m", age :"35" },
        {id : "5", name : "ikly", gender : "m", age :"41" },
        {id : "6", name : "ert", gender : "f", age :" 30" },
        {id : "7", name : "qwe", gender : "f", age :" 31" },
        {id : "8", name : "bdd", gender : "m", age :" 78" }
    ]
    var id_filter = ["1","4","5","8"], selectedIndividuals = []; 
    for( var i=individuals.length-1; i>=0; --i){ 
      if( id_filter.indexOf( individuals[i].id ) != -1 ){ 
        selectedIndividuals.push( individuals[i] ); 
      } 
    }
    console.log( selectedIndividuals );

Answer 20

    individuals = [
        {id : "1", name : "abc", gender : "m", age :"15" },
        {id : "2", name : "a", gender : "m", age :"25" },
        {id : "3", name : "efg", gender : "f", age :"5" },
        {id : "4", name : "hjk", gender : "m", age :"35" },
        {id : "5", name : "ikly", gender : "m", age :"41" },
        {id : "6", name : "ert", gender : "f", age :" 30" },
        {id : "7", name : "qwe", gender : "f", age :" 31" },
        {id : "8", name : "bdd", gender : "m", age :" 78" }
    ]
    var id_filter = ["1","4","5","8"], selectedIndividuals = []; 
    for( var i=individuals.length-1; i>=0; --i){ 
      if( id_filter.indexOf( individuals[i].id ) != -1 ){ 
        selectedIndividuals.push( individuals[i] ); 
      } 
    }
    console.log( selectedIndividuals );

How to selectively filter an array of objects using another array in JavaScript

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

Answer №8

Answer №9

Answer №10

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