How to merge two arrays in JavaScript and de-duplicate items

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I have two JavaScript
arrays:

var array1 =
            ["Vijendra","Singh"];
var array2 = ["Singh",
            "Shakya"];

I want the
output to be:

var
            array3 =
            ["Vijendra","Singh","Shakya"];

The
output array should have repeated words
removed.

How do I merge two arrays in JavaScript
so that I get only the unique items from each array in the same order they were inserted
into the original arrays?

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class="normal">Answer

To just
merge the arrays (without removing
duplicates)

ES5 version use
Array.concat:

class="snippet" data-lang="js" data-hide="false" data-console="true"
data-babel="false">

class="snippet-code-js lang-js prettyprint-override">var array1 =
["Vijendra", "Singh"];
var array2 = ["Singh",
"Shakya"];

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

ES6
version use href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment"
rel="noreferrer">destructuring

const
            array1 = ["Vijendra","Singh"];
const array2 = ["Singh",
            "Shakya"];
const array3 = [...array1,
            ...array2];

Since
there is no 'built in' way to remove duplicates ( href="http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf"
rel="noreferrer">ECMA-262 actually has
Array.forEach which would be great for this), we have to do it
manually:

Array.prototype.unique
            = function() {
 var a = this.concat();
 for(var i=0; i            ++i) {
 for(var j=i+1; j if(a[i] ===
            a[j])
 a.splice(j--, 1);
 }
 }


            return
            a;

};

Then,
to use it:

var array1 =
            ["Vijendra","Singh"];
var array2 = ["Singh", "Shakya"];
// Merges
            both arrays and gets unique items
var array3 = array1.concat(array2).unique();
            

This will
also preserve the order of the arrays (i.e, no sorting
needed).

Since many people are annoyed about
prototype augmentation of Array.prototype and for
in loops, here is a less invasive way to use
it:

function arrayUnique(array)
            {
 var a = array.concat();
 for(var i=0; i            {
 for(var j=i+1; j if(a[i] ===
            a[j])

 a.splice(j--, 1);
 }

            }

 return a;
}

var array1 =
            ["Vijendra","Singh"];
var array2 = ["Singh", "Shakya"];
 // Merges
            both arrays and gets unique items

var array3 =
            arrayUnique(array1.concat(array2));

For
those who are fortunate enough to work with browsers where ES5 is available, you can use
Object.defineProperty like
this:

Object.defineProperty(Array.prototype,
            'unique', {
 enumerable: false,
 configurable: false,

            writable: false,
 value: function() {

 var a =
            this.concat();
 for(var i=0; i for(var j=i+1;
            j if(a[i] === a[j])
 a.splice(j--,
            1);
 }
 }

 return a;

            }

});