Values are being subtracted correctly without displaying any negative results

Question

Values are being subtracted correctly without displaying any negative results

I'm working with the following code snippet:

const my_transactions = [{amount: -100,currency: 'EUR'},{amount: -200,currency: 'EUR'},{amount: -400,currency: 'EUR'}];
let total = 0;
my_transactions.forEach(el => total = total - el.amount);
console.log('total:',total);

All the amounts are negative in this code. The goal is to sum all the amounts and display the overall balance. In this scenario, the balance is negative. The expected output should be

-700

However, the variable "total" ends up with a positive value instead. What could be causing this unexpected behavior?

javascript

Answer 1

Answer №1

Subtracting a negative value is essentially the same as adding a positive value.

These calculations will yield the same outcome:

console.log('subtracting:', 0 - (-100));
console.log('adding:', 0 + (+100));

If your goal is to accumulate all these negative numbers to reach a total of -700, then opt to add them together instead of subtracting:

my_transactions.forEach(el => total = total + el.amount);

Answer 2

Subtracting a negative value is essentially the same as adding a positive value.

These calculations will yield the same outcome:

console.log('subtracting:', 0 - (-100));
console.log('adding:', 0 + (+100));

If your goal is to accumulate all these negative numbers to reach a total of -700, then opt to add them together instead of subtracting:

my_transactions.forEach(el => total = total + el.amount);

Answer 3

Answer №2

To switch from subtraction to addition, replace the minus (-) operator with the plus (+) operator.

Remember that subtracting a negative number is equivalent to adding a positive number.

const my_sales = [
  { amount: -100, currency: 'EUR' },
  { amount: -200, currency: 'EUR' },
  { amount: -400, currency: 'EUR' }
];

let total = 0;
my_sales.forEach(item => total = total + item.amount); // Change - to +

console.log('Total sales:', total);

An alternative and more efficient method is to use the reduce function:

const mySales = [
  { amount: -100, currency: 'EUR' },
  { amount: -200, currency: 'EUR' },
  { amount: -400, currency: 'EUR' }
];

let total = mySales.reduce((sum, { amount }) => sum + amount, 0);

console.log('Total sales:', total);

Answer 4

To switch from subtraction to addition, replace the minus (-) operator with the plus (+) operator.

Remember that subtracting a negative number is equivalent to adding a positive number.

const my_sales = [
  { amount: -100, currency: 'EUR' },
  { amount: -200, currency: 'EUR' },
  { amount: -400, currency: 'EUR' }
];

let total = 0;
my_sales.forEach(item => total = total + item.amount); // Change - to +

console.log('Total sales:', total);

An alternative and more efficient method is to use the reduce function:

const mySales = [
  { amount: -100, currency: 'EUR' },
  { amount: -200, currency: 'EUR' },
  { amount: -400, currency: 'EUR' }
];

let total = mySales.reduce((sum, { amount }) => sum + amount, 0);

console.log('Total sales:', total);

Answer 5

Answer №3

This is an addition, not subtraction

const my_transactions = 
  [{amount: -100,currency: 'EUR'},
   {amount: -200,currency: 'EUR'},
   {amount: -400,currency: 'EUR'}];
   
let total = 0;

my_transactions.forEach(el => total += el.amount);

console.log('total:', total);

For a more concise code:

const my_transactions = 
  [ { amount: -100, currency: 'EUR' }
  , { amount: -200, currency: 'EUR' }
  , { amount: -400, currency: 'EUR' }
  ];
let total = my_transactions.reduce((s,{amount:v}) => s + v, 0);

console.log('total:', total);

Answer 6

This is an addition, not subtraction

const my_transactions = 
  [{amount: -100,currency: 'EUR'},
   {amount: -200,currency: 'EUR'},
   {amount: -400,currency: 'EUR'}];
   
let total = 0;

my_transactions.forEach(el => total += el.amount);

console.log('total:', total);

For a more concise code:

const my_transactions = 
  [ { amount: -100, currency: 'EUR' }
  , { amount: -200, currency: 'EUR' }
  , { amount: -400, currency: 'EUR' }
  ];
let total = my_transactions.reduce((s,{amount:v}) => s + v, 0);

console.log('total:', total);

Values are being subtracted correctly without displaying any negative results

Answer №1

Answer №2

Answer №3

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