计算属性中出现意外的副作用

Question

我不知道为什么我的计算机属性错误会产生意外的副作用,如下所示.

错误:

 ?  https://google.com/#q=vue%2Fno-side-effects-in-computed-properties  Unexpected side effect in "orderMyReposByStars" computed property            
  src/components/HelloWorld.vue:84:14
        return this.myRepos.sort((a, b) => a.stargazers_count < b.stargazers_count)

HTML:

<div v-if="myRepos && myRepos.length > 0">
  <h3>My Repos</h3>
  <ul>
    <li v-for="repo in orderMyReposByStars" v-bind:key="repo.id">
      <div class="repo">
        {{repo.name}}
        <div class="pull-right">
          <i class="fas fa-star"></i>
          <span class="bold">{{repo.stargazers_count}}</span>
        </div>
      </div>
    </li>
  </ul>
</div>

JS:

export default {
  name: 'HelloWorld',
  data () {
    return {
      myRepos: null,  <-- THIS IS ULTIMATELY AN ARRAY OF OBJECTS
    }
  },
  computed: {
    orderMyReposByStars: function () {
      return this.myRepos.sort((a, b) => a.stargazers_count < b.stargazers_count)
    },
...

据我所知,这看起来是正确的https://vuejs.org/v2/guide/list.html#Displaying-Filtered-Sorted-Results

Answer 1

.sort 改变原始数组.

要避免它,请在排序之前克隆该数组.

.slice()克隆数组是最简单的方法之一.请参阅/sf/answers/1438346241/

return this.myRepos.slice().sort((a, b) => a.stargazers_count < b.stargazers_count)

在旁注,null.sort()或null.slice()将抛出错误.也许最好将初始值设置myRepos为空数组[]而不是null