I did the work below for javascript file for webpage. The change model button and change duration button are not working. please let me know why $.$ thank you

The instructions describe the missing logic that is needed; you will translate these into JavaScript in the places indicated.

You are encouraged to use the provided naming convention for ease of review.

$*/$

$/******************$ create variables $******************/$

$/*$ create variables to hold the values for modelName and duration $*/$

$//$ INSERT YOUR CODE HERE

let modelName $="$XYZ$"$;

let modelDuration $=0$;

$/******************$ helper function $******************/$

$/*$ create a function called recalculate$()$ which will

$-$ create a variable to represent the calculated$-$cost span element. That will look something like:

$//$ let costLabel $=$ document.getElementById$("$calculated$-$cost$")$;

$-$ check the value of the modelName variable, and use that to calculate the new total cost:

e$.$g$.$ if modelName is currently $"$XYZ$",$ duration $*100$ gives us the new total cost.

if modelName is currently $"$CPRG$",$ duration $*213$ gives us the new total cost.

$-$ set the value of the calculated$-$cost element's innerHTML to this new value

$*/$

$//$ INSERT YOUR CODE HERE

function recalculate$()\{$

let costLabel $=$ document.getElementById$("$calculated$-$cost$")$;

if $($modelName $==="$XYZ$")\{$

let totalCost $=$ modelDuration $*100$;

costLabel$.$innerHTML $=$ totalCost;

$\}$ else if $($modelName $==="$CPRG$")\{$

let totalCost $=$ modelDuration $*213$;

costLabel$.$innerHTML $=$ totalCost;

$\}$

$\}$

$/******************$ model button logic $******************/$

$/*$

$-$ first, create a variable to represent the "Switch Model" pseudo$-$button $($hint: can use getElementById$)$

$-$ second, create a function called changeModel$()$ which checks the value of the model name variable. This function will:

$-$ create a variable to represent the model$-$text span element

$-$ if modelName is currently $"$XYZ$",$ change the value of modelName to $"$CPRG$",$ and change the innerHTML of the model$-$text span element to "Model CPRG$"$

$-$ if modelName is currently $"$CPRG$",$ change the value of modelName to $"$XYZ$",$ and change the innerHTML of the model$-$text span element to "Model XYZ$"$

$-$ then, recalculate$()$ the total cost.

$-$ finally, uncomment the following line of JavaScript to have this function run automatically whenever the pseudo$-$button is clicked: $*/$

$//$ modelButton.addEventListener$("$click$",$ changeModel$)$;

$//$ INSERT YOUR CODE HERE

let modelButton $=$ document.getElementById$("$modelButton$")$;

function changeModel$()\{$

let modelText $=$ document.getElementById$("$model$-$text"$)$;

if $($modelName $==="$XYZ$")\{$

modelName $="$CPRG$"$;

modelText.innerHTML $=$ "Model CPRG$"$;

$\}$ else if $($modelName $==="$CPRG$")\{$

modelName $="$XYZ$"$;

modelText.innerHTML $=$ "Model XYZ$"$;

$\}$

recalculate$()$;

$\}$

modelButton.addEventListener$("$click$",$ changeModel$)$;

$/******************$ duration button logic $******************/$

$/*-$ first, create a variable to represent the "Change Duration" pseudo$-$button.

$-$ then, create a function called changeDuration$()$ that will

$-$ create a variable to represent the duration$-$text span element

$-$ prompt$()$ the user for a new duration

$-$ save the result of the prompt$()$ to the duration variable

$-$ change the innerHTML of the duration$-$text span element to this new value

$-$ recalculate$()$ the total cost$/$

$-$ finally, attach this function to the "Change Duration" pseudo$-$button, so it runs whenever the button is clicked.

$*/$

$//$ INSERT YOUR CODE HERE

let durationButton $=$ document.getElementById$("$durationButton$")$;

function changeDuration$()\{$

let durationText $=$ document.getElementById$("$duration$-$text"$)$;

var newDuration $=$ document.getElementById$("$durationInput$").$value;

if $($newDuration $!==$ null$)\{$

var duration $=+$newDuration;

durationText.innerHTML $=$ duration;

recalculate$()$;

$\}$

$\}$

durationButton.addEventListener$("$click$",$ changeDuration$)$;