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30-seconds-of-code/snippets/reduceSuccessive.md
Angelos Chalaris 611729214a Snippet format update
To match the starter (for the migration)
2019-08-13 10:29:12 +03:00

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---
title: reduceSuccessive
tags: array,function,intermediate
---
Applies a function against an accumulator and each element in the array (from left to right), returning an array of successively reduced values.
Use `Array.prototype.reduce()` to apply the given function to the given array, storing each new result.
```js
const reduceSuccessive = (arr, fn, acc) =>
arr.reduce((res, val, i, arr) => (res.push(fn(res.slice(-1)[0], val, i, arr)), res), [acc]);
```
```js
reduceSuccessive([1, 2, 3, 4, 5, 6], (acc, val) => acc + val, 0); // [0, 1, 3, 6, 10, 15, 21]
```