Make variable sum of two other variables after change

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Please look at the following code. There is an issue in it which I am struggling to understand:

let sideCount = 0;
let mealCount = 0;
let itemCount = sideCount + mealCount;

const pizzaOrder = ({size, crustType, topping, quantity}) => {
    quantity = Math.round(parseInt(quantity));
    mealCount += quantity;
    if (topping === "") {
        console.log(`Order: ${quantity} ${size.toTitleCase()} ${crustType.toLowerCase()} crust plain cheese pizza`);
    } else {
        console.log(`Order: ${quantity} ${size.toTitleCase()} ${crustType.toLowerCase()} crust ${topping} pizza`);
    }
    console.log(`Meal Count after ordering ${quantity} pizzas: ${mealCount}`);
    console.log(`Current item count: ${itemCount}`);        
};

(There's more, but this is what is important for the question)

I have looked all over StackOverflow for referencing and pass by value or pass by reference, but I couldn't find anything that solved my problem.

When I update mealCount, it doesn't change the value of itemCount. How do I fix this?

Order: 10 Medium thin crust pepperoni pizza 
Meal Count after ordering 10 pizzas: 10 
Current item count: 0 
Order: 3 burgers with Relish 
Meal Count after ordering burger: 13 
Current item count: 0 
Meal Count: 0 Side Count: 0 
Meal Count: 0 
Side Count: 0 
Meal Count: 0 
Side Count: 0 
Your total is $0.00. Enjoy your meal! 

Code is interpreted (evaluated) sequentially.

When you write: let itemCount = sideCount + mealCount;

You actually assign value of sideCount + mealCount to itemCount. At the very moment, sideCount and mealCount have value of "0", hence itemCount equals "0".

You calling function pizzaOrder and changing mealCount (inside this function) won't make javascript reevaluate once more addition of mentioned line (let itemCount = sideCount + mealCount).

Literally, pizzaOrder function does not affect variable "itemCount" at all.

One problem solution would be to add line: "itemCount = sideCount + mealCount" inside of pizzaOrder function, specifically under the line: "mealCount += quantity;".

So, your code would look like:

const pizzaOrder = ({size, crustType, topping, quantity}) => {
    quantity = Math.round(parseInt(quantity));
    mealCount += quantity;
    totalCount = mealCount + sideCount;
    if (topping === "") {
        console.log(`Order: ${quantity} ${size.toTitleCase()} ${crustType.toLowerCase()} crust plain cheese pizza`);
    } else {
        console.log(`Order: ${quantity} ${size.toTitleCase()} ${crustType.toLowerCase()} crust ${topping} pizza`);
    }
    console.log(`Meal Count after ordering ${quantity} pizzas: ${mealCount}`);
    console.log(`Current item count: ${itemCount}`);        
};

How would I make a variable that has the sum of two other variables , How would I make a variable that has the sum of two other variables in python? Notice how total is created after planned is deleted. integer(numbers ie: total = 14 + 2) to the variable total Delete total = 14 + 2 finally change  But you had it right, you can add two variables together with the + symbol. Also, a side note, when you print something, make sure whatever you want printed is in parentheses directly after print, otherwise python won't understand what you're telling it to do. You don't need to print anything here, so you can delete that code.

If you want to keep the "state" of your order you might want to use an object that can be exposed wherever you might need it:

const count = {
sideCount: 0,
mealCount: 0,
itemCount() {
    return this.sideCount + this.mealCount
  }
}

const pizzaOrder = ({size, crustType, topping, quantity}) => {
quantity = Math.round(parseInt(quantity));
count.mealCount += quantity;
if (topping === "") {
    console.log(`Order: ${quantity} ${size.toTitleCase()} ${crustType.toLowerCase()} crust plain cheese pizza`);
} else {
    console.log(`Order: ${quantity} ${size} ${crustType.toLowerCase()} crust ${topping} pizza`);
}
console.log(`Meal Count after ordering ${quantity} pizzas: ${count.mealCount}`);
console.log(`Current item count: ${count.itemCount()}`);        
};
console.log(count.itemCount()) // 0

pizzaOrder({size: 'asd', crustType: 'asd', topping: 'asd', quantity: 1})

console.log(count.itemCount()) // 1

As the other people mentioned your code won't work like that. Hope this helps.

How do I create a sum of different variables in SPSS for Windows?, in SPSS for Windows? For example, V1 V2 V3 V4 SUM 2 8 12 3 25. EXECUTE . You can also do the following if you have more variables: Thanks for contributing an answer to Mathematics Stack Exchange! Please be sure to answer the question. Provide details and share your research! But avoid … Asking for help, clarification, or responding to other answers. Making statements based on opinion; back them up with references or personal experience. Use MathJax to format equations.

Instead of adding the mealCount in each function, I returned the mealCount or sideCount or drinkCount in an object, like so

return {mealCount: quantity};

Then, I used the Array.prototype.reduce() method on the orders parameter of the groupOrder() function, a function that you call, pass an array of function calls to the food orders, with the food order and price calculations nested inside of it

let mealCount = orders.reduce((av, cv) => {
    if (cv.hasOwnProperty('mealCount')) {
        return {mealCount: av.mealCount + cv.mealCount};
    }
    return {mealCount: av.mealCount + 0};
}, {mealCount: 0}).mealCount;

Create a new variable based on existing data in Stata, Following are examples of how to create new variables in Stata using the To create a new variable (for example, total ) from the transformation of existing For additional help, see the help files within Stata (for each of the  To see the INDIRECT function in action, insert a new cell into cell D3. This shifts all of the other cells down. The new sum is the total of cells D3 to D7. The INDIRECT function dynamically changes the entire range to include the entire list you initially entered, plus the new cell you inserted as well.

Creating R Variables from Multiple Input Variables Using Code , Similarly, the following code computes a proportion for each observation: variables showing the frequency of consumption for six different colas on two usage occasions. One variable which shows the sum of the variables, called SUM, SUM. Optional: change the structure of the data so that it is categorical, by setting  Use the assignment operator <- to create new variables. A wide array of operators and functions are available here. # Three examples for doing the same computations. mydata$sum <- mydata$x1 + mydata$x2. mydata$mean <- (mydata$x1 + mydata$x2)/2. attach (mydata) mydata$sum <- x1 + x2. mydata$mean <- (x1 + x2)/2. detach (mydata)

My dependent variable= sum of two independent varibles , is it , Can i make an econometric model with two independent variables that are the sum With all of your suggestions, its better to change my independent variables in This sounds untenable, but I suppose it depends upon whether those two If one variable is the sum of two other variables, there is nothing to be estimated. To create a new variable (for example, total) from the transformation of existing variables (for example, the sum of v1, v2, v3, and v4 ), use: gen total = v1 + v2 + v3 + v4. Alternatively, use egen with the built-in rowtotal option: egen total = rowtotal (v1 v2 v3 v4) Note: The egen command treats missing values as 0.

Adding or Sum of Variables. Possible?, I overcame this by making the variable change only when the user clicks the "​submit" But I was wondering whether or not I could calculate the sum of different variables, if I decided to So in the results slide, I could show a total of the money earned from the two companies. Hi Phil. after 7 years, your post saved my day! This means that the sum of two independent normally distributed random variables is normal, with its mean being the sum of the two means, and its variance being the sum of the two variances (i.e., the square of the standard deviation is the sum of the squares of the standard deviations).

Comments
  • Have you called the pizza order function and then logged the itemCount?
  • Yes, I have. It shows 0.
  • There is no such thing like a reference to a variable in JS, what you are asking for is not possible. Make an itemCount() function that computes the sum on every call.
  • I have tons of other functions like pizza order. Does this mean I have to put this line in everyone of them, or is there a work around
  • @Marvin Make a function updateCount that is called from each of them :-) You will have to (more or less explicitly) do the recalculation either every time you change one of the input values or every time you need the output value.
  • With an object, you could even make it a getter property.
  • Does it have to be a method? Can I make it a property?