Go to the project$02-04.$html file in your code editor and in the head section add a script element to load

the project$02-04.$js file, deferring the loading the external script file until the entire page is loaded. Review the

hands$-$on projEcts $75$

contents of the HTML file, noting the ids of different page elements. You will display the calculated values in

span elements with ids of $$foodTotal$,$foodTax$,$ and $$totalBill$.$ Save your changes to the file.

$3.$ Go to the project$02-04.$js file in your code editor. Below the comment section, declare the following constants

with their initial values: CHICKEN$\_$PRICE $510\mathrm{.}95,$ HALIBUT$\_$PRICE $513\mathrm{.}95,$ BURGER$\_$PRICE $59\mathrm{.}95,$ SALMON$\_$

PRICE $518\mathrm{.}95,$ SALAD$\_$PRICE $57\mathrm{.}95,$ and SALES$\_$TAX $50\mathrm{.}07.$

$4.$ Create the calcTotal$()$ function containing the following:

a$.$ Declare the cost variable with an initial value of $0.$

b$.$ Declare the buyChicken variable equal to the checked property of the element with the id $$chicken$.$ In

the same way, declare the buyHalibut, buyBurger, buySalmon, and buySalad variables equal to the

checked property of elements with ids of $$halibut$,$burger$,$salmon$,$ and $$salad$,$ respectively.

c$.$ Use a comparison operator to increase the value of the cost variable by the value of the CHICKEN$\_$PRICE

constant if buyChicken is true or by $0$ if otherwise $($see Figure $2-21$ as an example of your code$).$ Do the

same for the buyHalibut, buyBurger, buySalmon, and buySalad variables, increasing the value of

total cost by the value of HALIBUT$\_$PRICE, BURGER$\_$PRICE, SALMON$\_$PRICE, and SALAD$\_$PRICE, respectively.

d$.$ Set the innerHTML property for the element with the id $$foodTotal$$ to the value returned by the

formatCurrency$()$ function using cost as the parameter value.

e$.$ Declare the tax variable, setting its value equal to the cost variable multiplied by SALES$\_$TAX.

f$.$ Set the innerHTML property for the element with the id $$foodTax$$ to the value returned by the

formatCurrency$()$ function using tax as the parameter value.

g$.$ Declare the totalCost variable, setting its value equal to the cost variable plus the tax variable.

h$.$ Set the innerHTML property for the element with the id $$totalBill$$ to the value returned by the

formatCurrency$()$ function using totalCost as the parameter value.

$5.$ Directly above the calcTotal$()$ function, insert an event handler that runs the calcTotal$()$ function when

the element with id $$chicken$$ is clicked. Repeat this for the elements with the id $$halibut$,$burger$,$salmon$,$

and $$salad$.$

$6.$ Save your changes to the file and then open project$02-04.$html in your web browser. Verify that when you click

each of the menu items the calculated cost and tax is automatically updated to reflect your choices.