Javascript - Stack and queues

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In programming data structures like stacks and queues,allows you to order items waiting to be processed.

We will see that implement these data structures under Javascript using pre-existing methods.

The Array


The JavaScript arrays. The most common example is:


var myArray = new Array(1, 2, 3, 4, 5) ;

Imagine that Javascript Stack and queues are nothing but the tables for which four methods can be used:
  • pop()
  • push()
  • shift()
  • unshift().

The stack: the FILO structure


FILO is an acronym meaning "First In Last Out". Here we will use the following methods:
  • push(): adds an element to the end of the array, thus increasing its size by one.
  • pop(): which removes the last element of the array, thereby reducing the size by 1.



Example a stack:
myArray.push(6);  // add a 6th element  
myArray.pop();   // we remove it   
myArray.pop();   // we remove the 6th element    
myArray.push(myArray.pop()); // no effect !      
/* The resulting array is [1|2|3|4] */

Queue: FIFO structure


FIFO is an acronym meaning "First In First Out". Here we will use the following methods:
  • push() adds an element to the end of the array.
  • shift() removes the first element of the array, thereby reducing the size by one, while shifting the elements to the left.


myArray.push(6);  // add the the 6th element      
myArray.shift();   // We remove the 1    
myArray.shift();   // We remove the 2       
myArray.push(myArray.shift()); // Put the first element at the last position!      
/* The resulting array is [4|5|6|3] */

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