How to return the matching results from Array of object based on an array of input values

Question

I have an array of objects like below

var item = [
    { "name": "John", "age": 30, "city": "New York1" },
    { "name": "John1", "age": 31, "city": "New York2" },
    { "name": "John2", "age": 32, "city": "New York3" },
    { "name": "John3", "age": 31, "city": "New York3" }
]

What I want is to get some of the age from this array of objects which has age property value in [30,31]

So basically the input will be an array of integers like var ageArray=[30,31];

Example :

Input : [30,31]

Output : Sum of the age of the below objects

 { "name":"John", "age":30, "city":"New York1"},
 { "name":"John1", "age":31, "city":"New York2"},
 { "name":"John3", "age":31, "city":"New York3"}

So here it will be

I have tried to use filter for this but not sure how can i use filter with contains

What I have tried is

var result = item .filter(obj => {
                    return obj.age..includes(ages);
                })

Can someone help me to resolve this ?

Mhmm where are the attempts you tried tho? Cuz you're basically just asking for someone to do it fully for you, which isn't how SO works, but I'm sure you're aware of that ;-) — Alexandre Elshobokshy
– Alexandre Elshobokshy, Commented Dec 31, 2018 at 13:23
@IslamElshobokshy I have tried using filters, I have mentioned it in the code , i didnt include the code that i have tried thats all — Arunprasanth K V
– Arunprasanth K V, Commented Dec 31, 2018 at 13:26

kemicofa · Accepted Answer · 2019-05-03 11:57:16Z

6

Use Array#reduce

const items = [
{ "name":"John", "age":30, "city":"New York1"},
{ "name":"John1", "age":31, "city":"New York2"},
{ "name":"John2", "age":32, "city":"New York3"},
{ "name":"John3", "age":31, "city":"New York3"}]


const ages = [30, 31];
const res = items.reduce((sum, {age})=>{
  return sum + (ages.includes(age) ? age : 0);
}, 0);

console.log(res);

Modified for names:

const items = [
{ "name":"John", "age":30, "city":"New York1"},
{ "name":"John1", "age":31, "city":"New York2"},
{ "name":"John2", "age":32, "city":"New York3"},
{ "name":"John3", "age":31, "city":"New York3"}]


const names = ["John", "john1"].map(n=>n.toLowerCase());
const res = items.reduce((sum, {name, age})=>{
  return sum + (names.includes(name.toLowerCase()) ? age : 0);
}, 0);

console.log(res);

edited May 3, 2019 at 11:57

answered Dec 31, 2018 at 13:19

kemicofa

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4 Comments

Arunprasanth K V Over a year ago

one doubt how can i do the same if the inputs are name example like ["john","john1"]?

kemicofa Over a year ago

@ArunprasanthKV yes, simply change sum += age to sum += 1 ... if you wish to count the occurences of the names.

Arunprasanth K V Over a year ago

not exactly. the inputs will be array of names and based on that i need to filter and get the sum of age

Arunprasanth K V Over a year ago

so reduce((sum, {age,name})if(ages.includes(name)){ sum += age; } this is enough right ?

Code Maniac · Accepted Answer · 2018-12-31 13:21:44Z

3

You can do it with reduce

var item= [{ "name":"John", "age":30, "city":"New York1"},{ "name":"John1", "age":31, "city":"New York2"},{ "name":"John2", "age":32, "city":"New York3"},{ "name":"John3", "age":31, "city":"New York3"}]

var ageArray=[30,31];


let op = item.reduce((o,c)=>{
  if( ageArray.includes(c.age) ) 
   { o+=c.age }
  return o;
},0)

console.log(op)

edited Dec 31, 2018 at 13:21

answered Dec 31, 2018 at 13:19

Code Maniac

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1 Comment

Arunprasanth K V Over a year ago

one doubt how can i do the same if the inputs are name example like ["john","john1"]?

Nina Scholz · Accepted Answer · 2018-12-31 13:44:59Z

3

You could use three steps

get only the ages
filter the ages with a Set
add remaining values

var items = [{ name: "John", age: 30, city:" New York1" }, { name: "John1", age: 31, city: "New York2" }, { name: "John2", age: 32, city: "New York3" }, { name: "John3", age: 31, city: "New York3" }],
    ageArray = [30, 31],
    result = items
        .map(({ age }) => age)
        .filter(Set.prototype.has, new Set(ageArray))
        .reduce((a, b) => a + b, 0);

console.log(result);

A slightly different approach for different keys to filter and to add.

var items = [{ name: "John", age: 30, city:" New York1" }, { name: "John1", age: 31, city: "New York2" }, { name: "John2", age: 32, city: "New York3" }, { name: "John3", age: 31, city: "New York3" }],
    names = ['John', 'John2'],
    result = items
        .filter((s => ({ name }) => s.has(name))(new Set(names)))
        .map(({ age }) => age)
        .reduce((a, b) => a + b, 0);

console.log(result);

edited Dec 31, 2018 at 13:44

answered Dec 31, 2018 at 13:24

Nina Scholz

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4 Comments

Arunprasanth K V Over a year ago

one doubt how can i do the same if the inputs are name example like ["john","john1"]?

Nina Scholz Over a year ago

@ArunprasanthKV, why not?

Arunprasanth K V Over a year ago

like i need to get the sum of age and the input will be array of names. can you please guide me to do the same too ?

Nina Scholz Over a year ago

oh, i see, you want some johns and the sum of ages of them, right?

adiga · Accepted Answer · 2018-12-31 13:26:07Z

2

You can use reduce to do this in one line:

const item = [{name:"John",age:30,city:"New York1"},{name:"John1",age:31,city:"New York2"},{name:"John2",age:32,city:"New York3"},{name:"John3",age:31,city:"New York3"}]
 ,ageArray = [30,31]
 ,total = item.reduce((sum, {age})=> sum += ageArray.includes(age) ? age : 0, 0);

console.log(total)

edited Dec 31, 2018 at 13:26

answered Dec 31, 2018 at 13:25

adiga

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2 Comments

Arunprasanth K V Over a year ago

one doubt how can i do the same if the inputs are name example like ["john","john1"]?

adiga Over a year ago

item.reduce((sum, {name, age})=> sum += ageArray.includes(name) ? age : 0, 0)

Mr code. · Accepted Answer · 2018-12-31 13:40:11Z

1

const items = [
   { "name":"John", "age":30, "city":"New York1"},
   { "name":"John1", "age":31, "city":"New York2"},
   { "name":"John2", "age":32, "city":"New York3"},
   { "name":"John3", "age":31, "city":"New York3"}
];
const ages = [30,31];
const result = items.filter(o => ages.find(o2 => o.age === o2)).map(o3 => o3.age);
console.log(result)
const reducer = (accumulator, currentValue) => accumulator + currentValue;
console.log(result.reduce(reducer))

answered Dec 31, 2018 at 13:40

Mr code.

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