How to extend an existing JavaScript array with another array, without creating a new array?

 

To extend an existing JavaScript array with another array without creating a new array, you can use the push() method to add elements from the second array to the end of the first array. Here's an example:

javascript

let array1 = [1, 2, 3];
let array2 = [4, 5, 6];

// Use the push() method to add elements from array2 to array1
for (let element of array2) {
    array1.push(element);
}

console.log("Extended array1:", array1);

Output:

less

Extended array1: [1, 2, 3, 4, 5, 6]

In this example:

• We have array1 containing [1, 2, 3] and array2 containing [4, 5, 6].
• We use a loop to iterate over each element in array2.
• For each element, we use the push() method to add it to the end of array1.
• After the loop, array1 is extended with the elements from array2.

Keep in mind that this approach modifies the original array1 directly. If you want to avoid modifying the original array and create a new array with the combined elements, you can use the spread operator or the concat() method:

Using the spread operator:

javascript

let extendedArray = [...array1, ...array2];
console.log("Extended array:", extendedArray);

Using the concat() method:

javascript

let extendedArray = array1.concat(array2);
console.log("Extended array:", extendedArray);

Both of these methods create a new array that contains the elements of both arrays, leaving the original arrays unchanged.