$1)$ Open the starter application$($zipped$)$ attached to this Assignment folder:

a$)$ Evaluations$\backslash$Assignments$\backslash$Assignment $2\backslash$Part$2-$invoice.zip

$2)$ Start the application and click the Calculate button without entering a subtotal or invoice date. An error message will be displayed indicating that the subtotal must be a number greater than zero.

$3)$ Enter a valid subtotal and click the Calculate button again. This time, the discount and invoice total will be calculated, but no invoice date or due date will be displayed.

$4)$ Code a function that formats the Date object that$$s passed to it in MM$/$DD$/$YYYY format and then returns the date string.

$5)$ Add code to the click$()$ event handler for the Calculate button that gets the invoice date and creates a Date object from it$.$

$6)$ Add code that checks whether the invoice date is not equal to an empty string and whether the Date object is not a valid date. If so$,$ display an error message, clear the controls, move the focus to the Invoice Date text box, and return.

$7)$ Add an if statement that checks whether the invoice date is equal to an empty string. If so$,$ use the current date as the default date. To do that, you$$ll need to get the current date and format it using the function you coded in step $4.$

$8)$ Add code that calculates the due date as $30$ days after the invoice date. Then, format that date.

$9)$ Add code that sets the values of the Invoice Date and Due Date fields.