 # Create a Queue Class

## Problem Explanation

• A Queue is an abstract Data Structure.

• A Queue folow FIFO/LILO principle.

• In this challenge we nede to implement `enqueue()`, `dequeue()`, `front()`, `size()`, `isEmpty()` methods.

• `enqueue()` - This method adds the element to the queue.
• `dequeue()` - This method removes the first element from the queue.
• `front()` - This method returns the first element in the queue that’d be dequeue’d.
• `size()` - This method returns the size of the queue.
• `isEmpty()` - This method returns if the queue is empty.
• DS Access Search Insert Delete
Queue n n 1 1
• ## Solutions

Solution 1 (Click to Show/Hide)

Note: This solution is not exactly a queue, the shift() method used in the dequeue() method is of complexity `O(n)` and not `O(1)`. However, the advanced solution rectifies this and uses Object(HashTables) instead of Array to implement Queue.

``````function Queue() {
var collection = [];
this.print = function() {
console.log(collection);
};
this.enqueue = function(val) {
collection.push(val);
};
this.dequeue = function() {
return collection.shift();
};
this.front = function() {
return collection;
};
this.size = function() {
return collection.length;
};
this.isEmpty = function() {
return collection.length === 0;
};
}
``````
Solution 2 (Click to Show/Hide)
``````class Queue {
constructor() {
this.collection = {};
this.start = 0;
this.end = 0;
}
print() {
console.log(this.collection);
}
enqueue(val) {
this.collection[this.end++] = val;
}
dequeue() {
return this.collection[this.start++];
}
front() {
return this.collection[this.start];
}
size() {
return this.end - this.start;
}
isEmpty() {
return this.size() === 0;
}
}
``````