'How to consecutively add values from one array to another and store the value in a new array in javascript?

I have 2 arrays:

const initialAmount = [50]

const transactionAmounts = [ -10, 10, 10, -1, -5, -10, 5, 5, 5, 10, 10, 10, 1, -1, -2, -5, -10 ]

How do i return an array that adds each value from transactionAmounts to the initialAmount? (excluding the first, which should be the initial value)

For example, it should return:

const valueAfterEachTransaction = [50, 40, 50, 60, 59, 54, 44, 49, 54, 59, 69, 79, 89, 90, 89, 87, 82, 72]

javascriptnode.jsreactjsalgorithmdata-structures


Solution 1:[1]

You could take a closure over the sum and get all elememts of both arrays for mapping the acutal sum.

const
    initial = [50],
    transactions = [-10, 10, 10, -1, -5, -10, 5, 5, 5, 10, 10, 10, 1, -1, -2, -5, -10],
    result = [...initial, ...transactions].map((s => v => s += v)(0));

console.log(...result);

Solution 2:[2]

const initialAmount = [50]

const transactionAmounts = [ -10, 10, 10, -1, -5, -10, 5, 5, 5, 10, 10, 10, 1, -1, -2, -5, -10 ]

const newArray = [initialAmount[0]]
let value = initialAmount[0]
let i = 0 

do {
    value = value + transactionAmounts[i]
  newArray[i+1] = value
  i++;
}
while (i < transactionAmounts.length);
 console.log(newArray)
const initialAmount = [50]

const transactionAmounts = [ -10, 10, 10, -1, -5, -10, 5, 5, 5, 10, 10, 10, 1, -1, -2, -5, -10 ]

const newArray = [initialAmount[0]]
let value = initialAmount[0]
let i = 0 

do {
    value = value + transactionAmounts[i]
  newArray[i+1] = value
  i++;
}
while (i < transactionAmounts.length);
 console.log(newArray)

Solution 3:[3]

Maybe I'm missing something here, but this seems to be a straightforward map, after you handle the missing initial value.

const combine = ([x], ys) => [0, ...ys] .map (y => x + y)

const initialAmount = [50]
const transactionAmounts = [-10, 10, 10, -1, -5, -10, 5, 5, 5, 10, 10, 10, 1, -1, -2, -5, -10] 

console .log (combine (initialAmount, transactionAmounts))
.as-console-wrapper {max-height: 100% !important; top: 0}

I'm curious of what your underlying need is. This seems an odd requirement. Why is the initial value passed in an array? Why is there an implied 0 to add to the first one. Is this an XY problem?

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Nina Scholz
Solution 2 hamid mehmood
Solution 3 Scott Sauyet

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