?Briefly explain the process of using arrays as data stacks.

What will be an ideal response?

?Arrays can be used to store information in a data structure known as a stack in which new items are added to the top of the stack-or to the end of the array-much like a person clearing a dinner table adds dishes to the top of a stack of dirty plates. A stack data structure employs the last-in first-out (LIFO) principle in which the last items added to the stack are the first ones removed. Stack data structures are encountered when using the Undo feature of some software applications, in which the last command a user performed is the first command that is undone.?JavaScript supports several methods to allow a user to work with a stack of array items. For example, thepush()method appends new items to the end of an array. It has the syntax
array.push(values)
wherevaluesis a comma-separated list of values to be appended to the end of the array. To remove-or unstack-the last item, thepop()method is used, as follows:
array.pop()
The following set of commands demonstrates how to use thepush()andpop()methods to employ the LIFO principle by adding and then removing items from a data stack:
var x = ["a", "b", "c"];x.push("d", "e"); // x = ["a", "b", "c", "d", "e"]x.pop(); // x = ["a", "b", "c", "d"]x.pop(); // x = ["a", "b", "c"]
In this code, thepush()method adds two items to the end of the array, and then thepop()method removes those last items one at a time.
A queue, which employs the first-in-first-out (FIFO) principle in which the first item added to the data list is the first removed, is similar to a stack. An example of the FIFO principle in action is a line of people waiting to be served. For array data that should be treated as a queue, the shift() method is used, which is similar to the pop()method except that it removes the first array item, not the last item. JavaScript also supports the unshift() method, which inserts new items at the front of the array.