Is there a way to check if two arrays have the same elements?

Question

Let say I have 2 arrays

firstArray  = [1, 2, 3, 4, 5];
secondArray = [5, 4, 3, 2, 1];

I want to know if they contain the same elements, whi

Answer 1

Well there is an Array.sort() method in JavaScript, and for comparing the (sorted) arrays, I think it's best to check out this question, as it is has a really good answer.

Especially note that comparing arrays as strings (e.g. by JSON.stringify) is a very bad idea, as values like "2,3" might break such a check.

Answer 2

Not in Vanila Javascript but in Angular there is option to match two objects.

angular.equals([1,2,3],[1,2,3])

Determines if two objects or two values are equivalent. Supports value types, regular expressions, arrays and objects.

See if this could help you.

alert("Match result of [1,2,3] &  [1,2,3] is "+angular.equals([1,2,3],[1,2,3]));

alert("Match result of [1,4,3] &  [1,2,3] is "+angular.equals([1,4,3],[1,2,3]));

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>

Click on Run Code snippet. If this solves your need please mark it as as Answer :)

In case order is not important and array is of number type.

var a1 = [1, 2, 3];
var a2 = [2, 1, 3];
//In case order is not important and array is of number type.
alert(eval(JSON.stringify(a1).replace(/,/g, "+").replace(/\[/g, "").replace(/\]/g, "")) === eval(JSON.stringify(a2).replace(/,/g, "+").replace(/\[/g, "").replace(/\]/g, "")));

Answer 3

Here's a working implementation using Vanilla JS:

function haveMatchingElements(firstArray, secondArray) {
    var stringsInFirstArray = parse(firstArray, 'string'),
        stringsInSecondArray = parse(secondArray, 'string'),
        numbersInFirstArray = parse(firstArray, 'number'),
        numbersInSecondArray = parse(secondArray, 'number'),
        stringResults = compare(stringsInFirstArray, stringsInSecondArray),
        numberResults = compare(numbersInFirstArray, numbersInSecondArray);

    if (stringResults && numberResults) {
        return true;
    } return false;

    function parse(array, type) {
        var arr = [];
        arr = array.sort().filter(function(index) {
            if (typeof index == type)
                return index;
        });
        return arr;
    }

    function compare(firstArray, secondArray) {
        if (firstArray.length !== secondArray.length)
            return false;
        for (var i = firstArray.length; i--;) {
            if (firstArray[i] !== secondArray[i])
                return false;
        }
        return true;
    }
}

This parses strings an numbers into different arrays and checks them separately. That will correct the issue of 1 and "1" matching as true due to the implicit type conversion caused by the sort function.

The implementation is simple:

var arr1 = ['1', 1];
var arr2 = [1, '1'];

var results = haveMatchingElements(arr1, arr2);
console.log(results); // true  

Answer 4

Using jQuery

You can compare the two arrays using jQuery:

// example arrays:
var firstArray  = [ 1, 2, 3, 4, 5 ];
var secondArray = [ 5, 4, 3, 2, 1 ];

// compare arrays:
var isSameSet = function( arr1, arr2 ) {
  return  $( arr1 ).not( arr2 ).length === 0 && $( arr2 ).not( arr1 ).length === 0;  
}

// get comparison result as boolean:
var result = isSameSet( firstArray, secondArray );

Here is a JsFiddle Demo

See this question helpful answer