Javascript - check two arrays for same value

Question

I have three arrays. One with static values, the other one has dynamic values, one array which will be filled with values that are the equal in the two arrays.

I would like to loop through the arrays and search for equal values. When a equal value has been found, this value should be put inside another array.

Something like this:

Array1 = ["Store1", "Store2", "Store3", "Store4"]; Array2 = ["Store6", "Store1", "Store3", "Store999"]; MatchedArray = ["Store1", "Store3"]; // should be filled with this

However, I don't like the idea of two for loops, like this:

 for(var arr1 = 0; arr1 < Array1.length; i++){ for(var arr2 = 0; arr2 < Array2.length; i++){ if(Array1[arr1].toLowerCase() == Array2[arr2].toLowerCase(){ console.log('store found'); duplicateArray.push(Array1[i].toLowerCase()); } } }

I would like to know how I can use the .map or filter function or some other ways to accomplish this.

Possible duplicate of Simplest code for array intersection in javascript — user3297291
– user3297291, Commented Apr 3, 2018 at 10:43
You're right. Think this one can be closed due to duplication. — Elvira
– Elvira, Commented Apr 3, 2018 at 10:55

Zenoo · Accepted Answer · 2018-04-03 09:44:00Z

You can use a combination of Array#filter and Array#includes :

const arr1 = [ 'Store1', 'Store2', 'Store3', 'Store4']; let arr2 = [ 'Store6', 'Store1', 'Store3', 'Store999']; let res = arr2.filter(e => arr1.includes(e)); console.log(res);

ashwintastic · Accepted Answer · 2018-04-03 09:56:45Z

Or make a generic array intersection function

 var intersection = function(){ return Array.from(arguments).reduce(function(previous, current){ return previous.filter(function(element){ return current.indexOf(element) > -1; }); }); }; var x = intersection([1,2,3],[2,3,4]); // or pass n number of array as an argument console.log(x);

Ori Drori · Accepted Answer · 2018-04-03 09:43:46Z

Filter one of the arrays, and check if the other one contains the item using Array.includes():

var Array1 = [ 'Store1', 'Store2', 'Store3', 'Store4']; var Array2 = [ 'Store6', 'Store1', 'Store3', 'Store999']; var MatchedArray = Array1.filter(function(s) { return Array2.includes(s); }); console.log(MatchedArray);

There are so many answers.. But I've chosen this one to test it out. :)

dchan · Accepted Answer · 2018-04-03 09:44:49Z

var Array1 = [ "Store1", "Store2", "Store3", "Store4"]; var Array2 = [ "Store6", "Store1", "Store3", "Store999"]; var Array3 = Array1 .filter(function(val) { return Array2 .indexOf(val) != -1; }); Array3 (2) ["Store1", "Store3"]

Shreyas Kumar · Accepted Answer · 2018-04-03 09:50:11Z

You can use array.filter method to get the desired result,

var filtered = arr1.filter(function(val) { return arr2.indexOf(val) >= 0 })

This function is filtering array items based on the given condition. The condition here is I'm checking whether the val is present in arr2 or not.

Niklesh Raut · Accepted Answer · 2018-04-03 09:58:30Z

If you consider Underscore.js here is the way for such kind of operation, for any number of array

var Array1 = [ 'Store1', 'Store2', 'Store3', 'Store4']; var Array2 = [ 'Store6', 'Store1', 'Store3', 'Store999']; var Array3 = [ 'Store1', 'Store5', 'Store3', 'Store201']; var common = _.intersection( Array1 ,Array2, Array3); console.log(common);

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>

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