通过过滤函数划分数组 [英] Dividing an array by filter function

问题描述

我有一个Javascript数组，我希望根据每个元素上调用的函数返回 true 或 false 。从本质上讲，这是一个 array.filter ，但我还想了解过滤 out 的元素。

I have a Javascript array that I would like to split into two based on whether a function called on each element returns true or false. Essentially, this is an array.filter, but I'd like to also have on hand the elements that were filtered out.

目前，我的计划是使用 array.forEach 并在每个元素上调用谓词函数。根据这是真还是假，我将当前元素推送到两个新数组中的一个。是否有更优雅或更好的方法来做到这一点？一个 array.filter 例如，在返回 false 之前，它会将元素推送到另一个数组？

Currently, my plan is to use array.forEach and call the predicate function on each element. Depending on whether this is true or false, I will push the current element onto one of the two new arrays. Is there a more elegant or otherwise better way to do this? An array.filter where the will push the element onto another array before it returns false, for instance?

推荐答案

使用ES6，您可以使用带有reduce的扩展语法：

With ES6 you can make use of the spread syntax with reduce:

function partition(array, isValid) {
  return array.reduce(([pass, fail], elem) => {
    return isValid(elem) ? [[...pass, elem], fail] : [pass, [...fail, elem]];
  }, [[], []]);
}

const [pass, fail] = partition(myArray, (e) => e > 5);

或单行：

const [pass, fail] = a.reduce(([p, f], e) => (e > 5 ? [[...p, e], f] : [p, [...f, e]]), [[], []]);

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