## JavaScript Data Structures: Exercise-4 with Solution

Write a JavaScript program to get the head and tail of a Doubly Linked Lists.

Sample Solution:

JavaScript Code:

``````class Node {
constructor(value) {
this.value = value;
this.next = null;
this.previous = null;
}
}

constructor(value) {
value: value,
next: null,
previous: null
};
this.length = 0;
}

// Insert node at end of the list

this.tail = newNode;
}
else
{
newNode.previous = this.tail;
this.tail.next = newNode;
this.tail = newNode;
}

this.length++;
}

}

get_Tail(){
return this.tail;
}

printList() {
let result = [];
while (current !== null) {
result.push(current.value);
current = current.next;
}
console.log(result.join(' '));
return this;
}
}

numList.printList();
console.log("Tail");
new_numList.printList();
console.log("Tail");
```
```

Sample Output:

``` "Original Doubly Linked Lists:"
" 2 3 5 6 8"
[object Object] {
next: [object Object] {
next: [object Object] { ... },
previous: [circular object Object],
value: 2
},
previous: null,
value: undefined
}
"Tail"
[object Object] {
next: null,
previous: [object Object] {
next: [circular object Object],
previous: [object Object] { ... },
value: 6
},
value: 8
}
""
[object Object] {
next: null,
previous: null,
value: undefined
}
"Tail"
[object Object] {
next: null,
previous: null,
value: undefined
}
```

Flowchart:

Live Demo:

See the Pen javascript-doubly-linked-list-exercise-4 by w3resource (@w3resource) on CodePen.

Improve this sample solution and post your code through Disqus

Linked List Previous: Count number of nodes in a Doubly Linked Lists.
Linked List Next: Insert a new node at any position of a Doubly Linked List.

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.

﻿

## JavaScript: Tips of the Day

Shorten an array using its length property

A great way of shortening an array is by redefining its length property.

```let array = [0, 1, 2, 3, 4, 5, 6, 6, 8, 9]
array.length = 4
// Result: [0, 1, 2, 3]
```

Important to know though is that this is a destructive way of changing the array. This means you lose all the other values that used to be in the array.

Ref: https://bit.ly/2LBj213