CODEWITHSUNDEEP
javascript
Shijil Narayanan
Shijil Narayanan

Reputation: 1019

Loop through two arrays and get a desired output using javascript

I have two arrays as follows

const arr1 = ['john', 'robot'];

const arr2 = [{name : 'john'}, {name : 'kevin'}, {name : 'james}];

My desired output is to manipulate array arr1 such that if value of arr1 is not present as a name property in arr2 it should get removed from arr1;

So in the above example after the operation, the output should be

console.log(arr1)  // ['john']

as robot is not present in arr2, it gets removed.

Likewise if I have following set of arrays

const names = ['sachin', 'sehwag'];

const players = [{name : 'dhoni'}, {name : 'dravid'}, {name : 'ganguly'} , {name : 'laxman}];

names array should be manipulated to 

console.log(names) // []

as both sachin and sehwag is not present in players array

Please help.Thanks in advance.

Upvotes: 0

Views: 51

Answers (4)

Mark
Mark

Reputation: 92440

If you can use es6, a Set is good for this. They only store unique values and are efficient at lookup. They give constant time lookups, which looping through an array doesn't:

const arr1 = ['john', 'robot'];
const arr2 = [{name : 'john'}, {name : 'kevin'}, {name : 'james'}];

// create a set with names
let testSet = arr2.reduce((set, obj) => set.add(obj.name), new Set)

let filtered = arr1.filter(item => testSet.has(item))
console.log(filtered)

Upvotes: 3

wizzwizz4
wizzwizz4

Reputation: 6426

This sounds like a job for [].filter:

function doTheThingYouWantItToDo(a, b) {
    return a.filter(function(elem) {
        for (var i = 0; i < b.length; i+=1) {
            if (b[i].name == elem) {
                return true;
            }
        }
        return false;
    });
}

Upvotes: -1

Arup Rakshit
Arup Rakshit

Reputation: 118261

You can first grab all the names from array of objects arr2, and then filter the arr1 based on names list..

var arr1 = ["john", "robot"];
var arr2 = [{ name: "john" }, { name: "kevin" }, { name: "james" }];
var names = arr2.map(ob => ob.name);
console.log(arr1.filter(name => names.includes(name)));

var arr1 = ["sachin", "sehwag"];
var arr2 = [
  { name: "dhoni" },
  { name: "dravid" },
  { name: "ganguly" },
  { name: "laxman" }
];
var names = arr2.map(ob => ob.name);
console.log(arr1.filter(name => names.includes(name)));

Upvotes: 2

Saurabh Yadav
Saurabh Yadav

Reputation: 3386

       const arr1 = ['john', 'robot'];
       const arr2 = [{name : 'john'}, {name : 'kevin'}, {name : 'james'}];
        var newArray= [];
        for(var i in arr2) {
            var content = arr2[i]['name'];
              if(arr1.indexOf(content) > -1){
                   newArray.push(content);
                }
        }

    console.log(newArray);

Hope it helps you!

Upvotes: 1

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