如果我没有误解的话，你可以用一种更易读的方式来做这件事：

function likeOrDislike(likedPhotoId) {
    // Get value or define empty
    const likedStored = localStorage.getItem("likedIds") || "[]";
    // Convert string into array
    let likedArray = JSON.parse(likedStored);
    
    // Check if exists or not
    if (likedArray.includes(likedPhotoId)) {
        // Remove from array
        likedArray = likedArray.filter(
            (photo) => photo !== likedPhotoId
        );
    } else {
        // Add to Array
        likedArray.push(likedPhotoId);
    }
    // Convert to string to store in localStorage
    const stringLiked = JSON.stringify(likedArray);
    localStorage.setItem("likedIds", stringLiked);
}

我很难理解你的代码中的逻辑，但我很确定这能满足你的用例。你的代码从来没有达到第一个条件的问题特别令人困惑，因为在我的测试中没有发生过这种情况。

// when repeating strings in code, it's useful to set them
// as variables so your autocomplete and linter can help you out
const likedStorageKey = 'likedUserIds'
const dislikedStorageKey = 'dislikedUserIds'

// using JSON is a little easier than manually building and splitting the list
const storageListOrDefault = (key) =>
  JSON.parse(localStorage.getItem(key)) || []

const setStorageItem = (key, list) =>
  localStorage.setItem(key, JSON.stringify(list))

// if an item is in the list, remove it
const removeFromOppositeList = (storageKey, toRemove) => {
  const vals = storageListOrDefault(storageKey)
  setStorageItem(storageKey, vals.filter((id) => id !== toRemove))
}

const toggleInList = (storageKey, toAdd) => {
  const vals = storageListOrDefault(storageKey)
  // here we filter the old list, assuming you want your like/dislike
  // buttons to have a 'neutral' state.
  // if the array already includes the item and you're toggling to a neutral
  // state, we remove the id
  // if the list doesn't include the id, we concat the id to the array, and sort
  const newList = vals.includes(toAdd)
    ? vals.filter((x) => x === toAdd)
    : [...vals, toAdd].sort()
  setStorageItem(storageKey, newList)
}

// onClick functions for your like and dislike buttons
const handleLike = (id) => {
  if (id) {
    removeFromOppositeList(dislikedStorageKey, id)
    toggleInList(likedStorageKey, id)
  }
}

const handleDislike = (id) => {
  if (id) {
    removeFromOppositeList(likedStorageKey, id)
    toggleInList(dislikedStorageKey, id)
  }
}

性能说明：所有这些都不是特别有效，但是如果您担心性能，我建议您使用一个专为这种具有持久性的状态管理而设计的库。