How to find single matching value in two arrays in js

Question

i have a two arrays.

 var a = ["a","b","c","d"];
 var b = ["c","d","f","k"];

These are my two arrays.Now i need to check any single matching values in two arrays.it should break after finding single match value.

My expect result was c and d matches.

what result do you expect? what have you tried? what is not working? — Nina Scholz, Sep 12 '17 at 11:58
How, if it breaks when it finds a single matching value, would you expect the result to be C & D? — Steve, Sep 12 '17 at 12:13
This will help: https://stackoverflow.com/questions/1885557/simplest-code-for-array-intersection-in-javascript?noredirect=1&lq=1 — mohsen, Jul 31 '23 at 12:59

Ori Drori · Accepted Answer · 2017-09-12T12:05:09.417

1

You can use Array#find to iterate one of the arrays, and Array#indexOf or Array#includes to find if the item exists in 2nd array:

var a = ["a", "b", "c", "d"];
var b = ["c", "d", "f", "k"];

function findMatch(arr1, arr2) {
  return arr1.find(function(item) {
    return arr2.indexOf(item) === -1;
  });
}

var result = findMatch(a, b);

console.log(result);

And a fancy version with arrow functions and consts:

const a = ["a","b","c","d"];
const b = ["c","d","f","k"];

const findMatch = (arr1, arr2) => arr1.find((item) =>  arr2.includes(item));

const result = findMatch(a, b);

console.log(result);

edited Sep 12 '17 at 12:05

answered Sep 12 '17 at 11:58

Ori Drori

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Why use [ES7](http://2ality.com/2016/01/ecmascript-2016.html) with includes, and do not use arrow functions to simplify `findMatch`? :) `arr1.find(item => arr2.includes(item));` – Orelsanpls Sep 12 '17 at 12:02

score 0 · Answer 2 · answered Sep 12 '17 at 11:58

If you just wanna know if there is duplicate content, this will work :

 a.some(x => b.some(y => y === x));

Will gives you true in case of duplicate content.

If you want every matching content in an array

a.filter(x => b.some(y => x === y));

will gives you ['c', 'd']

score 0 · Answer 3 · answered Sep 12 '17 at 12:00

you can do it in the following way

var a = ["a","b","c","d"];
 var b = ["c","d","f","k"];
 
 let ans = a.reduce(function(x, y){
    if(x == null){
        if(b.indexOf(y) > -1){
            return y;
        }
    }
    return x;
 }, null);
 
 console.log(ans);

score 0 · Answer 4 · answered Sep 12 '17 at 12:01

I loop through the first array once and check the index of each value in the second array.

If the index is > -1, then push it onto the returned array.

Array.prototype.diff = function(arr2) {
    var ret = [];
    for(var i in this) {   
        if(arr2.indexOf( this[i] ) > -1){
            ret.push( this[i] );
        }
    }
    return ret;
};

var array1 = ["cat", "sum","fun", "run", "hut"];
var array2 = ["bat", "cat","dog","sun", "hut", "gut"];

console.log( array1.diff(array2) );

score 0 · Answer 5 · answered Sep 12 '17 at 12:11

You can use filter() and every() to achieve what you want:

var a = ["a","b","c","d"];
var b = ["c","dx","f","k"];
var isMatched = false;
    result = a.filter(x =>{
        b.every(s => { return isMatched = s!==x});
      });
   
console.log(!isMatched);

How to find single matching value in two arrays in js

5 Answers5