Array.Filter不更新数组 [英] Array.Filter not updating array

问题描述

任务是:

系统会为您提供一个初始数组(驱逐舰函数)，然后是一个或多个参数.移除所有初始数组中与这些元素具有相同值的元素争论.

You will be provided with an initial array (the first argument in the destroyer function), followed by one or more arguments. Remove all elements from the initial array that are of the same value as these arguments.

在研究它的过程中，我发现一些Array.filter行为难以理解:

While working through it I found some Array.filter behaviour I'm struggling to understand:

function destroyer(arr) {
  for (var i = 1; i<arguments.length; i++){
    toDelete = arguments[i];
    arr.filter(isItIn);
  }
  return arr;
}

function isItIn(item, undefined, array){
  return item!=toDelete;
}

destroyer([1, 2, 3, 1, 2, 3], 2, 3);

我的目的是遍历参数的1+项，每次都调用 arr.filter .然后 Arr.filter 调用 isItIn ，它检查当前检查的项目是否是我要搜索的项目.但是， arr 不变地返回.当我将 isItIn 更改为:

My intent here was to iterate through items 1+ of the arguments, calling arr.filter each time. Arr.filter then calls isItIn which checks if the currently examined item is the one I'm searching for. However, arr is being returned unchanged. When I change isItIn to:

function isItIn(item, undefined, array){
  return item==1;
}

要测试，它仍然没有改变，但是 isItIn 的原始著作中的 console.log s表明它正确地接收了参数(或者据我所知)已经考虑过要确定.

to test, it is still unchanged, however console.logs in the original writing of isItIn show that it is receiving the arguments correctly (or so far as I've thought to determine at least.

请注意，我已经通过另一条途径解决了该问题，我不是在寻找解决问题的方法，而只是解释我的初始代码出了什么问题.

Please note, I've solved the problem through another route, I'm not looking for a solution to the problem, merely an explanation of where my initial code went wrong.

推荐答案

基本上，您使用

Basically you use Array#filter and omit the result of it.

您需要将filter的结果分配给前一个数组.

You need to assign the result of filter to the former array.

arr = arr.filter(isItIn);

function destroyer(arr) {
    for (var i = 1; i < arguments.length; i++) {
        toDelete = arguments[i];
        arr = arr.filter(isItIn);
    }
    return arr;
}

function isItIn(item) {
    return item != toDelete;
}

console.log(destroyer([1, 2, 3, 1, 2, 3], 2, 3));

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