如何通过改变数组的进程从数组中删除元素？

Question

我有一组这样的对象：

const jokes = [
  {jokeId: 255, jokeText: "había un borrachín en un boliche", categoryId: "284"},
  {jokeId: 243, jokeText: "había una borrachín en un boliche", categoryId: "284"},
  {jokeId: 554, jokeText: "había otro borrachín en un boliche", categoryId: "284"},
  {jokeId: 424, jokeText: "jodido loco el tipo", categoryId: "256"},
  {jokeId: 257, jokeText: "había un loco en el manicomio", categoryId: "256"},
  {jokeId: 579, jokeText: "remamado estaba!", categoryId: "836"},
];

我唯一需要做的就是 delete/remove 所有 categoryId = 256 的对象，改变 jokes 数组。我尝试将 filter 与 splice 方法（ES6 方法）链接起来，但我做不到。

Answer 1

let jokes =
[
  {jokeId: 255, jokeText: "había un borrachín en un boliche", categoryId: "284"},
  {jokeId: 243, jokeText: "había una borrachín en un boliche", categoryId: "284"},
  {jokeId: 554, jokeText: "había otro borrachín en un boliche", categoryId: "284"},
  {jokeId: 424, jokeText: "jodido loco el tipo", categoryId: "256"},
  {jokeId: 257, jokeText: "había un loco en el manicomio", categoryId: "256"},
  {jokeId: 579, jokeText: "remamado estaba!", categoryId: "836"},
];
const result = jokes.filter(item => item.categoryId !== "256");
console.log(result);

Answer 2

let jokes =
[
{jokeId: 255, jokeText: "había un borrachín en un boliche", categoryId: "284"},
{jokeId: 243, jokeText: "había una borrachín en un boliche", categoryId: "284"},
{jokeId: 554, jokeText: "había otro borrachín en un boliche", categoryId: "284"},
{jokeId: 424, jokeText: "jodido loco el tipo", categoryId: "256"},
{jokeId: 257, jokeText: "había un loco en el manicomio", categoryId: "256"},
{jokeId: 579, jokeText: "remamado estaba!", categoryId: "836"},
];
const filtredJokes = jokes.filter(joke => joke.categoryId !== '256')
console.log(filtredJokes )

Answer 3

如果您想要一个简单的 ES6 方法，您可以使用过滤器覆盖“jokes”的值。

jokes = jokes.filter(joke => joke.categoryId !== "256");

Answer 4

就地执行此操作（修改现有数组）的最简单方法是遍历数组，找到要删除的元素的索引并调用 .splice()，如下所示：

const jokes =
[
    {jokeId: 255, jokeText: "había un borrachín en un boliche", categoryId: "284"},
    {jokeId: 243, jokeText: "había una borrachín en un boliche", categoryId: "284"},
    {jokeId: 554, jokeText: "había otro borrachín en un boliche", categoryId: "284"},
    {jokeId: 424, jokeText: "jodido loco el tipo", categoryId: "256"},
    {jokeId: 257, jokeText: "había un loco en el manicomio", categoryId: "256"},
    {jokeId: 579, jokeText: "remamado estaba!", categoryId: "836"},
];

let remove = []

for (let i = 0; i < jokes.length; i++) {
    if (jokes[i].categoryId == 256) {
        remove.push(i)
    }
}

// every splice() call shifts next items
let removed = 0
for (let idx of remove) {
    jokes.splice(idx - removed, 1)
    removed += 1
}

console.log(jokes)

Answer 5

The only thing I need to do is to delete/remove all the objects with categoryId = 256, mutating the jokes array. I've tried to chain a filter with a splice method (ES6 approach), but I could not do it.

在某些情况下，例如 OP 遇到的情况，无法将过滤后的结果重新分配给原始源引用。喜欢...

const arr = [1, 2, 3]; arr = arr.filter(/* ... */);

...这将失败。一个人可能还需要处理不允许写入但仍然可以改变的属性。

使用与 OP 已经尝试过的完全相同的方法 ("...我尝试将 filter 与 splice 方法链接起来..." )，可以将此类问题的解决方案归纳为 mutating remove 实现，基于回调，正是 filter 要求的那种，这里的回调函数是判断是否移除数组项的条件...

function removeEveryMatchingItemByCondition(arr, condition, target) {
  target = (target ?? null);

  let idx = arr.length;
  const copy = Array.from(arr);

  // Processing the array from RIGHT to LEFT keeps the `idx` always in sync
  // with both related array items, the one of the mutated and also the one
  // of the unmutated version of the processed array reference.
  // Thus the `condition` always gets passed the unmutated shallow copy.

  while (idx) {
    if (arr.hasOwnProperty(--idx)) { // take a *sparse array* into account.

      // - keep processing the unmutated shallow copy by the `condition` method.
      // - arguments list ...[elm, idx, arr]... invoked within `target` context.
      if (condition.call(target, copy[idx], idx, copy)) {

        arr.splice(idx, 1); // mutate processed array.
      }
    }
  }
  return arr; // return the mutated array reference.
}


const jokes = [
  {jokeId: 255, jokeText: "había un borrachín en un boliche", categoryId: "284"},
  {jokeId: 243, jokeText: "había una borrachín en un boliche", categoryId: "284"},
  {jokeId: 554, jokeText: "había otro borrachín en un boliche", categoryId: "284"},
  {jokeId: 424, jokeText: "jodido loco el tipo", categoryId: "256"},
  {jokeId: 257, jokeText: "había un loco en el manicomio", categoryId: "256"},
  {jokeId: 579, jokeText: "remamado estaba!", categoryId: "836"},
];

removeEveryMatchingItemByCondition(
  jokes,
  // exactly what the OP was asking for in first place.
  (({ categoryId }) => categoryId === '256')
);
console.log({ jokes });

removeEveryMatchingItemByCondition(
  jokes,
  (({ categoryId }) => categoryId === '284')
);
console.log({ jokes });

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如何通过改变数组的进程从数组中删除元素？

How does one remove elements from an array by a process that does mutate this array?

javascript

arrays

object

mutation