computed 属性第一次会返回 null

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#104 3 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
25/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
typescript
Domain
frontend

Research direction

Start by reproducing the reported computed setup with the TypeScript example and inspect when the computed state value is initialized. Confirm that the first value is a string rather than null and that the component warning no longer occurs.

Written by the indexing model from the issue text.

Description

我按照如下方式使用 computed，但是第一次 state 会返回 null，导致我的组件警告提示，说传入了一个 null，但是需要 string

  data: {
    isConnected: true,
  },
  computed: {
    text({ isConnected }) {
      return isConnected ? "网络正常" : "网络异常";
    },
    state({ isConnected }) {
      return isConnected ? "success" : "error";
    },
  },
  lifetimes: {
    attached() {
      wx.onNetworkStatusChange((res) => {
        this.setData({
          isConnected: res.isConnected,
        });
      });
    },
  },
Dominant language
TypeScript
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