Find duplicates in jquery array using unique

I have the following JS arrays.

$arrTest1 = ['46819', '46819', '46819'];
$arrTest2 = ['46819', '46802', '46819'];

let len1 = arrTest1.length;
let len2 = $.unique(arrTest1).length; 

if (len1 > len2) {
  alert('Found duplicate');
} else {
  alert('Did not find duplicate');
}


let len3 = arrTest2.length;
let len4 = $.unique(arrTest2).length; 

if (len3 > len4) {
  alert('Found duplicate');
} else {
  alert('Did not find duplicate');
}

For first array $arrTest1 its working and showing found duplicate but for $arrTest2 its showing as Did not find duplicate. Did I missed something?

$.unique is not working for $arrTest2 whereas for $arrTest1 it works fine.

Documentation:

> Description: Sorts an array of DOM elements, in place, with the
> duplicates removed. Note that this only works on arrays of DOM
> elements, not strings or numbers.

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<!-- language: lang-js -->

$arrTest1 = ['46819', '46819', '46819'];
$arrTest2 = ['46819', '46802', '46819'];

let len1 = $arrTest1.length;
let len2 = [...new Set($arrTest1)].length; 

if (len1 > len2) {
  alert('Found duplicate');
} else {
  alert('Did not find duplicate');
}


let len3 = $arrTest2.length;
let len4 = [...new Set($arrTest2)].length; 

if (len3 > len4) {
  alert('Found duplicate');
} else {
  alert('Did not find duplicate');
}

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<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

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You can use Set like my example

You can use

1. $.merge() is used to combine array1 and array2 into combinedArray.
2. $.grep() is used to filter combinedArray and find the duplicate values, which are stored in duplicateValues.

Refer below Code

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<!-- language: lang-js -->

$arrTest1 = ['46819', '46819', '46819'];
$arrTest2 = ['46819', '46802', '46819'];

const combinedArray = $.merge($.merge([], $arrTest1), $arrTest2);

// Find duplicate values
const duplicateValues = $.grep(combinedArray, function (element, index) {
  return index !== $.inArray(element, combinedArray);
});

if(duplicateValues.length) {
  alert('Found duplicate');
} else {
  alert('Did not find duplicate');
}

<!-- language: lang-html -->

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<!-- end snippet -->

$.unique has be removed in V.3.0 and above you can do it using $.grep()

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

var arrTest1 = ['46819', '46819', '46819'];
var arrTest2 = ['46819', '46802', '46819'];

var duplicatesTest1 = $.grep(arrTest1, function (e, i) {
    return $.inArray(e, arrTest1) !== i;
});

if (duplicatesTest1.length > 0) {
    alert('Found duplicate in arrTest1');
} else {
    alert('Did not find duplicate in arrTest1');
}

var duplicatesTest2 = $.grep(arrTest2, function (e, i) {
    return $.inArray(e, arrTest2) !== i;
});

if (duplicatesTest2.length > 0) {
    alert('Found duplicate in arrTest2');
} else {
    alert('Did not find duplicate in arrTest2');
}

<!-- language: lang-html -->

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<!-- end snippet -->