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30-seconds-of-code/snippets/reduceSuccessive.md
Mathias Bynens 8ee50178f3 Avoid confusing prototype methods for static methods
Correct: `Array.from()` (it’s a static method)
Incorrect: `Array.join()` (doesn’t exist; it’s a prototype method)

This patch uses the common `#` syntax to denote `.prototype.`.
2018-09-28 15:44:12 -04:00

526 B

reduceSuccessive

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.

const reduceSuccessive = (arr, fn, acc) =>
  arr.reduce((res, val, i, arr) => (res.push(fn(res.slice(-1)[0], val, i, arr)), res), [acc]);
reduceSuccessive([1, 2, 3, 4, 5, 6], (acc, val) => acc + val, 0); // [0, 1, 3, 6, 10, 15, 21]