# Inserting New Nodes in a Singly Linked List in JavaScript

When working with data structures in JavaScript, it’s important to understand how to insert new nodes into a singly linked list. A singly linked list is a collection of nodes where each node has a reference to the next node in the list. Unlike arrays, linked lists do not have a fixed size and can grow or shrink as needed.

Inserting a new node into a singly linked list involves creating a new node and updating the references of the adjacent nodes to point to the new node. There are several scenarios to consider when inserting a new node:

• If the list is empty, the new node becomes the head of the list.
• If the new node is to be inserted at the beginning of the list, the new node becomes the new head of the list.
• If the new node is to be inserted at the end of the list, the new node becomes the new tail of the list.
• If the new node is to be inserted at a specific position, the references of the adjacent nodes need to be updated accordingly.

It’s important to consider the time complexity of inserting a new node into a singly linked list. In the best case scenario, when inserting at the beginning or end of the list, the time complexity is O(1) since only a constant number of operations are needed. However, in the worst case scenario, when inserting at a specific position, the time complexity is O(n) since the entire list may need to be traversed to find the correct position.

In conclusion, inserting new nodes into a singly linked list in JavaScript requires careful consideration of the list’s structure and the position of the new node. By understanding the concept of linked lists and the different scenarios for inserting nodes, you can effectively manipulate and update the data stored in the list.

## Overview of Singly Linked List

A singly linked list is a type of data structure that consists of a sequence of nodes. Each node contains an element and a reference (or link) to the next node in the sequence. The first node is called the head, while the last node has a reference to null.

One of the main advantages of a singly linked list is its dynamic size, as elements can be easily added or removed without the need to allocate a fixed amount of memory in advance. This makes it a suitable choice for scenarios where the number of elements is unknown or fluctuates over time.

Inserting a new node into a singly linked list involves updating the references of the adjacent nodes to include the new node. This can be done efficiently in constant time, regardless of the size of the list. However, finding a specific node in a singly linked list requires traversing through the entire list, resulting in a time complexity of O(n), where n is the number of nodes in the list.

Overall, a singly linked list is a simple yet versatile data structure that provides a flexible approach to managing data. Its simplicity makes it easy to implement and understand, making it a popular choice for many programming tasks.

## What is a Singly Linked List?

A singly linked list is a data structure used in computer science to store a collection of elements. It consists of a series of nodes, where each node contains a value and a pointer to the next node in the list. The first node in the list is called the «head» node and the last node is called the «tail» node.

The advantage of using a singly linked list is that it can easily be modified by inserting or deleting nodes at the beginning or end of the list. However, accessing nodes in the middle of the list can be time-consuming as you have to traverse the list from the beginning.

To represent a singly linked list in JavaScript, you can create a class or object that has properties for the head and tail nodes. The head property points to the first node in the list, while the tail property points to the last node. Each node has a value property and a next property that points to the next node in the list.

Node 1Node 2Node 3
Value: 5Value: 10Value: 15
Next: Node 2Next: Node 3Next: null

In the example above, the linked list consists of three nodes. Node 1 has a value of 5 and points to Node 2. Node 2 has a value of 10 and points to Node 3. Node 3 has a value of 15 and points to null, indicating the end of the list.

## Inserting New Nodes into a Singly Linked List

A singly linked list is a data structure consisting of a sequence of nodes, where each node contains a value and a reference to the next node in the list. Inserting new nodes into a singly linked list involves adding a new node at a specified position in the list.

To insert a new node into a singly linked list, you need to perform the following steps:

1. Create a new node with the desired value.
2. Traverse the list to find the position where you want to insert the new node.
3. Update the references of the previous node and the new node to include the new node in the list.

For example, suppose we have a singly linked list with the following nodes:

```head -> A -> B -> C -> D -> null
```

If we want to insert a new node with the value «X» between nodes B and C, we would perform the following steps:

1. Create a new node with the value «X».
2. Traverse the list to find node B.
3. Update the reference of node B to point to the new node, and update the reference of the new node to point to node C.

The resulting linked list would be:

```head -> A -> B -> X -> C -> D -> null
```

Inserting new nodes into a singly linked list is an important operation that allows you to modify the structure of the list and add new elements. It is commonly used in various algorithms and data structures.

Overall, understanding how to insert new nodes into a singly linked list is essential for working with linked lists and solving related programming problems. It is an important concept to master in order to become a proficient programmer.

## Approaches for Insertion

When it comes to inserting new nodes into a singly linked list in JavaScript, there are several approaches that can be used depending on the desired functionality and efficiency.

• Inserting at the beginning: This approach involves adding the new node at the beginning of the linked list. It requires updating the next pointer of the new node to point to the current head of the list, and then updating the head to point to the new node.
• Inserting at the end: In this approach, the new node is added at the end of the linked list. It requires iterating through the list until reaching the last node, and then updating the next pointer of the last node to point to the new node.
• Inserting at a specific position: This approach allows inserting a new node at a specific position in the linked list. It requires traversing the list to find the node that should precede the new node, updating the next pointer of the new node to point to the next node, and updating the next pointer of the preceding node to point to the new node.

Each approach has its own advantages and disadvantages, and the choice of approach depends on the specific requirements and constraints of the problem at hand. It is important to consider factors such as time complexity, space complexity, and the expected size of the linked list when deciding which approach to use.

## Inserting at the Beginning

When inserting a new node at the beginning of a singly linked list in JavaScript, we need to perform the following steps:

1. Create a new node and assign its value.
2. Make the next pointer of the new node point to the current head of the linked list.
3. Update the head pointer to point to the new node.

To visualize this process, let’s consider the following example:

Head -> A -> B -> CA -> value: 5
B -> value: 10
C -> value: 15

Suppose we want to insert a new node with a value of 20 at the beginning of the linked list. The steps to perform this insertion would be as follows:

1. Create a new node with a value of 20.
2. Make the next pointer of the new node point to the current head node, which is node A.
3. Update the head pointer to point to the new node. Now, the new head node is the newly created node.

After the insertion, the modified linked list and memory would look like this:

Head -> 20 -> A -> B -> C20 -> value: 20
A -> value: 5
B -> value: 10
C -> value: 15

This is how we can insert a new node at the beginning of a singly linked list in JavaScript.

## Inserting in the Middle

Inserting a new node in the middle of a singly linked list involves updating the references of the adjacent nodes.

To insert a new node, we first need to find the position where we want to insert it. We can iterate through the list until we find the desired position or reach the end of the list.

Once we have found the position, we can create a new node and set its value. Then, we update the references of the adjacent nodes to point to the new node. This ensures that the new node is properly inserted into the list.

Here is an example of inserting a new node with a value of 3 after the second node:

``````const insertInMiddle = (list, value) => {
let current = list.head;
let previous = null;
// Find the position to insert the new node
while (current !== null && current.value !== 2) {
previous = current;
current = current.next;
}
// Create a new node
const newNode = {
value: value,
next: null
};
// Update the references of the adjacent nodes
newNode.next = current.next;
current.next = newNode;
};
// Example usage
const list = {
value: 1,
next: {
value: 2,
next: {
value: 4,
next: null
}
}
}
};
insertInMiddle(list, 3);
``````

After inserting the new node, the updated list will be:

``````1 -> 2 -> 3 -> 4
``````

Inserting nodes in the middle can be useful when we need to maintain the order of the elements in the list or when we want to insert a value in a specific position.

## Inserting at the End

One common operation when working with a singly linked list is inserting a new node at the end. This can be useful when adding new elements to the list or when appending data to an existing list.

To insert a new node at the end of a singly linked list, you can follow these steps:

1. Create a new node with the desired data.
2. If the list is empty (head is null), set the head to point to the new node.
3. Otherwise, traverse the list by starting at the head and moving to the next node until reaching the last node.
4. Set the next pointer of the last node to point to the new node.

Here’s an example implementation in JavaScript:

``````
class Node {
constructor(data) {
this.data = data;
this.next = null;
}
}
constructor() {
}
insertAtEnd(data) {
const newNode = new Node(data);
if (this.head === null) {
} else {
let currentNode = this.head;
while (currentNode.next) {
currentNode = currentNode.next;
}
currentNode.next = newNode;
}
}
}
``````

With the above implementation, you can easily insert a new node at the end of a singly linked list by calling the `insertAtEnd` method and passing in the desired data. The method will take care of creating a new node and updating the appropriate pointers.

By following these steps, you can efficiently insert new nodes at the end of a singly linked list in JavaScript.

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