JavaScript implementation of one-way linked list
- Linked list data structure
- Create linked list
- Append elements to the end of the list
- Insert elements anywhere in the list
- Remove an element from the specified location in the linked list
- View the index of the element
- Remove specified element
- isEmpty, size, getHead method
1. Linked list data structure
A linked list stores an ordered set of elements, but unlike an array, elements in a linked list are not placed consecutively in memory. Each element consists of a node that stores the element itself and a pointer to the next element.
2. Create a linked list
function LinkedList() {
let Node = function(element) {
this.element = element;
this.next = null;
};
let length = 0;
let head = null;
this.append = function(element) {};
this.insert = function(positon, ele) {};
this.removeAt = function(positon) {};
this.remove = function(element) {};
this.indexOf = function(element) {};
this.isEmpty = function() {};
this.size = function() {};
this.getHead = function() {};
this.toString = function() {};
this.print = function() {};
}
3. Add elements to the end of the list
Implement an append method
this.append = function(element) {
let node = new Node(element),
current;
if (head === null) {
head = node;
} else {
// Last item found
current = head;
while(current.next) {
current = current.next;
}
// Find the last item, assign its next as node, and establish a link
current.next = node;
};
length++;
};
4. Insert elements anywhere in the list
this.insert = function(position, element) {
if (position > -1 && position < length) {
let current = head,
previous,
index = 0;
// Insert element first
let node = new Node(element);
if (position === 0) {
node.next = current;
head = node;
} else {
while (index++ > position) {
previous = current;
current = current.next;
}
// Connect previous to node and node to current
node.next = current;
previous.next = node;
}
length++;
return true;
} else {
return false;
}
};
5. Remove the element from the specified position of the linked list
// Remove element at given location
this.removeAt = function(position) {
// Check the out of range value
if (position > -1 && position < length) {
let current = head,
previous,
index = 0;
// Remove first
if (position === 0) {
head = current.next;
} else {
while (index ++ < position) {
previous = current;
current = current.next;
}
// Connect previous with the next item of current, skip current
previous.next = current.next;
}
length--;
// Return removed elements
return current.element;
} else {
return null;
}
};
6. View the index of the element
this.indexOf = function(element) {
let current = head,
index = 0;
while (current) {
if (element === current.element) {
return index;
} else {
index++;
current = current.next;
}
}
return -1;
};
7. Remove the element at the specified location
this.remove = function(element) {
let index = this.indexOf(element);
return removeAt(index);
};
8. isEmpty, size, getHead method
this.isEmpty = function() {
return length === 0;
};
this.size = function() {
return length;
};
this.getHead = function() {
return head;
};
Complete code
function LinkedList() {
let Node = function(element) {
this.element = element;
this.next = null;
};
let length = 0;
let head = null;
this.append = function(element) {
let node = new Node(element),
current;
if (head === null) {
head = node;
} else {
// Last item found
current = head;
while(current.next) {
current = current.next;
}
// Find the last item, assign its next as node, and establish a link
current.next = node;
};
length++;
};
this.insert = function(position, element) {
if (position > -1 && position < length) {
let current = head,
previous,
index = 0;
// Insert element first
let node = new Node(element);
if (position === 0) {
node.next = current;
head = node;
} else {
while (index++ > position) {
previous = current;
current = current.next;
}
// Connect previous to node, and node to current
node.next = current;
previous.next = node;
}
length++;
return true;
} else {
return false;
}
};
this.removeAt = function(position) {
// Check the out of range value
if (position > -1 && position < length) {
let current = head,
previous,
index = 0;
// Remove first
if (position === 0) {
head = current.next;
} else {
while (index++ < position) {
previous = current;
current = current.next;
}
// Connect previous with the next item of current, skip current
previous.next = current.next;
}
length--;
// Return removed elements
return current.element;
} else {
return false;
}
};
this.remove = function(element) {
let index = this.indexOf(element);
return removeAt(index);
};
this.indexOf = function(element) {
let current = head,
index = 0;
while (current) {
if (element === current.element) {
return index;
} else {
index++;
current = current.next;
}
}
return -1;
};
this.isEmpty = function() {
return length === 0;
};
this.size = function() {
return length;
};
this.getHead = function() {
return head;
};
this.toString = function() {
let current = head,
string = '';
while(current) {
string += current.element + (current.next ? 'n' : '');
current = current.next;
}
return string;
};
}