JavaScript Program to Create an Array of Unique Values From Multiple Arrays Using Set Object

We have given multiple arrays consisting of numerical values, and our task is to create an output array that consists of unique values from the multiple input arrays. We will use the Set object in JavaScript language.

Example:

Input: 
         inputarray1: [1,2,3,4,5]  
         inputarray2: [4,5,6,7,8] 
Output: 
         outputArray: [1,2,3,4,5,6,7,8]

Using Set and Spread Operator

In this approach, we are using the Set object and the spread operator to create a new array that contains unique values from the input arrays. Here, the function can handle any number of input arrays. The spread operator combines the input arrays into a single array and then we wrap with the Set object so that automatically duplicate elements are removed and unique elements are stored.

Syntax:

function function_name(...arrays) {
//statements
}

Example: This example shows the use of the above-explained approach.

Javascript

function mergeUsingSpread(
    ...inputArrays
) {
    let uniqueValues = new Set();

    // Using loop to go thofugh each array
    inputArrays.forEach((arr) => {

        // Here, adding the element of current
        // array into the Set of uniqueValues
        arr.forEach((ele) => {
            uniqueValues.add(ele);
        });
    });

    // Converting the set to array
    return Array.from(uniqueValues);
}

// Multiple Input arrays
let inputArray1 = [1, 2, 3, 4, 5];
let inputArray2 = [4, 5, 6, 7, 8];
let inputArray3 = [7, 8, 9, 10, 11];
let outputArray = mergeUsingSpread(
    inputArray1,
    inputArray2,
    inputArray3
);
console.log(outputArray);

Output

[
   1, 2, 3, 4,  5,
   6, 7, 8, 9, 10,
  11
]

Using the Concat method and Set

In this approach, we have used the concat method in the function merge. Using concat, we are handling multiple input arrays and merging them into a single array. Using the set, we are then removing duplicate elements and converting them to arrays, then printing the output.

Syntax:

let newArray = Array.prototype.concat.apply([], arguments)

Example: This example shows the use of the above-explained approach.

Javascript

function mergeUsingConcat() {

    // We are merging all arrays
    // in one array
    let allMergedArr =
        Array.prototype.concat.apply(
            [],
            arguments
        );

    // We are Removing the duplicate
    // using Set and converting it to array
    return Array.from(
        new Set(allMergedArr)
    );
}

// Multiple input arrys. You can
// increase and pass to the function
let inputArray1 = [1, 2, 3, 4, 5];
let inputArray2 = [4, 5, 6, 7, 8];
let inputArray3 = [7, 8, 9, 10, 11];
let outputArray = mergeUsingConcat(
    inputArray1,
    inputArray2,
    inputArray3
);

//Output is displayed
console.log(outputArray);

Output

[
   1, 2, 3, 4,  5,
   6, 7, 8, 9, 10,
  11
]

Using Reduce method with the Set

In this approach, we are using the reduce method to and the forEach method to iterate over all the input arrays, and all this is stored in the set, where the unqualified values are considered. Later, we will convert this set into an array and print the result.

Syntax:

return Array.prototype.reduce.call(arguments, function (res, currentArr) {
  // Iterate through the current array
}, new Set());

Example: This example shows the use of the above-explained approach.

Javascript

function mergeUsingReduce() {

    // Reduce method will merge the
    // multiple input arrays in single set here.
    return Array.prototype.reduce.call(
        arguments,
        function (res, currentArr) {

            // Iterate over each element
            // in the currentArray.
            currentArr.forEach(
                function (ele) {
                    res.add(ele);
                }
            );
            return res;
        },
        new Set()
    );
}

// Multiple input arrys. You can increase
// and pass to the function
let inputArray1 = [1, 2, 3, 4, 5];
let inputArray2 = [4, 5, 6, 7, 8];
let inputArray3 = [7, 8, 9, 10, 11];
let tempresult = mergeUsingReduce(
    inputArray1,
    inputArray2,
    inputArray3
);

// We are converting Set to the array
// and printing it.
let outputArray =
    Array.from(tempresult);
console.log(outputArray);

Output

[
   1, 2, 3, 4,  5,
   6, 7, 8, 9, 10,
  11
]