Interview Preparations

Array

1.What are the different strategies to merge two arrays?

There are multiple strategies to merge two arrays in JavaScript:

Using the concat() method: The concat() method can be used to concatenate two or more arrays into a new array. It returns a new array that contains elements from both arrays.

Example:
```
const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const mergedArray = arr1.concat(arr2);
console.log(mergedArray); // Output: [1, 2, 3, 4, 5, 6]
```
Using the spread operator: The spread operator (...) can be used to spread the elements of one array into another. It creates a new array with the elements from both arrays.

Example:
```
const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const mergedArray = [...arr1, ...arr2];
console.log(mergedArray); // Output: [1, 2, 3, 4, 5, 6]
```
Using the push() method: The push() method can be used to add elements from one array into another. It modifies the original array and returns the new length of the array.

Example:
```
const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
arr1.push(...arr2);
console.log(arr1); // Output: [1, 2, 3, 4, 5, 6]
```
Using the splice() method: The splice() method can be used to add elements from one array into another at a specified index. It modifies the original array and returns the removed elements.

Example:
```
const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
arr1.splice(2, 0, ...arr2);
console.log(arr1); // Output: [1, 2, 4, 5, 6, 3]
```

Using the concat() method with spread operator: The concat() method can be used with spread operator (...) to merge two or more arrays into a new array.

Example:

const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const mergedArray = [].concat(...arr1, ...arr2);
console.log(mergedArray); // Output: [1, 2, 3, 4, 5, 6]

2.How do you remove duplicate elements from an array in JavaScript? Provide an example.

To remove duplicate elements from an array in JavaScript, one approach is to use the Set object which allows only unique values, and then convert the set back to an array. Here's an example:

const arr = [1, 2, 3, 3, 4, 5, 5];
const uniqueArr = [...new Set(arr)];
console.log(uniqueArr); // Output: [1, 2, 3, 4, 5]

In this example, the Set object is created with the original array arr, which contains duplicate elements. Then, the spread syntax (...) is used to convert the set back to an array and assign it to the uniqueArr variable. The resulting uniqueArr array contains only the unique elements from the original array.

3.What is the syntax to add a new element at the beginning of an array in JavaScript?

To add a new element at the beginning of an array in JavaScript, you can use the unshift() method. The syntax is as follows:

array.unshift(newElement);

Where array is the array to which the element needs to be added, and newElement is the new element to be added.

Here is an example:

const arr = [2, 3, 4];
arr.unshift(1);
console.log(arr); // Output: [1, 2, 3, 4]

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