What should I do if the uniapp loop event does not take effect?

Recently when using uniapp for development, I encountered a problem that loop events did not take effect. During the processing, I found some reasons that may cause the loop event to not take effect, which I will share with you below.

1. The index in the loop event is not used correctly

In the loop event in uniapp, you can use index to represent the index value of the current element in the array. If used carelessly, the loop event will not take effect. For example, the following code:

<template>
  <div>
    <div v-for="(item, index) in list" :key="index">
      <span @click="deleteItem(index)">{{item}}</span>
    </div>
  </div>
</template>
<script>
export default {
  data() {
    return {
      list: [1, 2, 3]
    }
  },
  methods: {
    deleteItem(index) {
      this.list.splice(index, 1)
    }
  }
}
</script>

In the above code, index represents the index value of the current element in the array. If used incorrectly, the deletion will not take effect. The correct way to use it is to pass index as a parameter to the method, and then use list.splice(index,1) to delete the corresponding element.

2. The mutation method is used in the loop event

In uniapp, the mutation method is specially used to modify the data in the state, and modification operations can only be performed in the mutation method. . If the mutation method is used in a loop event, the loop event will not take effect. Therefore, direct use of mutation methods should be avoided in loop events.

3. Asynchronous operations are used in loop events

Asynchronous operations may be involved in loop events, such as network requests, timers, etc. If there is no reasonable handling, the cyclic event will not take effect. Therefore, you should avoid using asynchronous operations in loop events, or use appropriate methods for asynchronous operations, such as using async and await.

4. The child component does not use the key attribute in the loop event

In uniapp, when the data of the child component changes, the child component will be re-rendered. If the key attribute is not used, it will cause sub-component rendering errors. Therefore, subcomponents in loop events should use the key attribute to ensure the uniqueness of each subcomponent.

Summary:

The above is a summary of my experience in dealing with the problem of loop events not taking effect during the development process of using uniapp. In order to ensure the normal operation of cyclic events, we should pay attention to handling related issues in cyclic events to avoid causing the cyclic events to not take effect.

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