Question 384338 in Javascript Question posted in
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Javascript – JS arrays how to calculate total of all children and update state when a condition is checked

I’m using ReactJS and I want to do some check and update state

Example : I have an array like this : const array=[70, 180, 70, 70] and another value const totalValue=350

I want to map on the array and add each element to the previous one, and when the amount is greather than totalValue I should stop and update state.

for Example : 70 + 180 = 250 so I should continue
70+80+70 = 320 I should continue

70+ 180+ 70+ 70 = 390 ;
So I should stop and update my state to 3 (3 is the length of the array when I’ve stopped)

I’ve tried a map and some array[index] but it’s hard to understand..
This is what I’ve tried :

[ 70, 180, 70, 70 ].map((el,index,array) => {
return el + array[index]
})

Sorry for my english

[ 70, 180, 70, 70 ].map((el,index,array) => { return el + array[index] })

Tags:

2

Answers


  1. 0

    This simply uses a for loop to achieve your needed result. This might not be the best way to do it, though.

    const totalValue = 350
const array = [70,180,70,70]

function calcSumAndState(total, arr) {
    var sum = 0,i = 0
  for (i = 0; i<arr.length; i++) {
    sum+=arr[i]
    if (sum > total) {
        break;
    }
  }
  return {
    sum:sum,
    state:i
  }
}
var s = calcSumAndState(totalValue, array)
console.log(s.sum)
console.log(s.state)
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  2. 0

    A while loop may be a good solution. Keep a running a total and check that the sum + the next value isn’t more than the maximum you’ve defined

    const maximum = 350;
const array = [ 70, 180, 70, 70 ];

let i = 0;
let sum = 0;
while (array[i] && (sum + array[i]) < maximum) {
    sum += array[i];
  i++;
}
console.log("sum",sum)

    .

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