Why does the page of changing component values ​​in uniapp not update?

With the continuous development of mobile development technology, many new frameworks or technical tools have emerged. Among them, uniapp is a cross-platform development framework. Based on the advantages of the Vue framework and small program development technology, it can quickly develop Apps for Android and iOS operating systems. However, when developing with uniapp, we may encounter some problems. For example, sometimes after changing the value of a component, the page is not updated. What is going on?

1. Uniapp component communication

In the development of uniapp, component communication is very common. We can achieve data transfer between components in many ways. Among them, it is very common for parent components to pass data to child components. We can use props to achieve this purpose.

2. Page update after changing component value

When using props to transfer data to sub-components, we generally maintain a data state in the parent component and pass this state to the parent component through props. Subassembly. However, after the parent component changed this state, the child component was not updated.

For this problem, uniapp actually provides a very practical watch syntax, which can monitor data changes and perform corresponding operations. The specific usage is as follows:

// 子组件
export default {
  props: {
    value: {
      type: String,
      default: ''
    }
  },
  data() {
    return {
      dataValue: this.value
    }
  },
  watch: {
    value(newVal) {
      this.dataValue = newVal
    }
  },
  methods: {
    handleOnChange(e) {
      this.$emit('input', e.target.value)
    }
  }
}

// 父组件
export default {
  data() {
    return {
      inputValue: ''
    }
  },
  methods: {
    handleInputChange() {
      this.inputValue = 'hello world'
    }
  }
}

In the above code, we can see that a dataValue state is defined in the child component, and the value changes passed by the parent component are monitored through watch and operated, ensuring that the child component Components always get the latest data.

3. Summary

In uniapp development, by using props and watch, we can very conveniently implement the parent component to transfer data to the child component, and ensure that the child component always gets the latest data. I hope this article can help you with the problems you encounter during development.

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