How to get sum consecutive array elements [duplicate]

Question

I have a array with 4 element. I want to get a new array which calculates the sum of array elements where number of opereands increases one at a time.

For example I have an array [1000, 2000, 2000, 4000]. Result array should be like

[ 1000, 1000 + 2000, 1000 + 2000 + 2000, 1000 + 2000 + 2000 + 4000]

i.e [1000, 3000, 5000, 9000]

var array = [1000, 2000, 2000, 4000];

var newArray = array.map((e,i) => e)

console.log(newArray);

Is there any way to do that using map function ? Or any other way ?

var numbers1 = [1000, 2000, 2000, 4000]; var numbers2 = numbers1.map(myFunction) function myFunction(value, index, array) { var i= 0; while (index > i) { index--; value = value + array[index]; } return value ; } — Vikash sah
– Vikash sah, Commented Mar 11, 2019 at 19:18

Reza · Accepted Answer · 2019-03-11 18:52:25Z

3

    const array = [1000, 2000, 2000, 4000];
    const result = array.reduce((acc,item, index) => { 
      if (index === 0) { acc.push(item); }
      else {
        acc.push(acc[index-1] + item);
      }
      return acc;
    } ,[]);
    console.log(result);

edited Mar 11, 2019 at 18:52

answered Mar 11, 2019 at 18:46

Reza

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Comments

moronator · Accepted Answer · 2019-03-11 18:45:33Z

1

Just loop through you original array and before you add the value to your new Array, add the last Value of the new Array to it.

var array = [1000, 2000, 2000, 4000];

var newArray = [];
for(n of array){
  if(newArray.length>0) newArray.push(newArray[newArray.length-1]+n)
  else newArray.push(n)
}

console.log(newArray);

answered Mar 11, 2019 at 18:45

moronator

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