$forceUpdate in Vue forces updates

Vue is a popular JavaScript framework for building interactive web pages. The virtual DOM mechanism it introduces makes updating views more efficient and faster.

However, sometimes we may need to force the view of a component to be updated even if the data has not changed. At this time, you need to use the $forceUpdate method provided by Vue.

$forceUpdate is a method in the Vue instance, which will force the view of the current component to be updated, even if the data has not changed. But be aware that doing so may cause performance issues because Vue will recalculate the view tree and re-render the components.

Using the $forceUpdate method is very simple. We only need to call it in the Vue instance, for example:

export default {
  data() {
    return {
      count: 0
    };
  },
  methods: {
    increment() {
      this.count++;
      this.$forceUpdate();
    }
  }
}

In this example, we define a data variable count and a method increment. When the increment method is called, we increment the count variable and then call the $forceUpdate method to force the component's view to be updated.

It should be noted that the $forceUpdate method will only act on the current component and its subcomponents. If we want to update the view of the parent component, we can use the $emit method to trigger a custom event.

// 子组件
<template>
  <button @click="increment">{{ count }}</button>
</template>

export default {
  props: ['count'],
  methods: {
    increment() {
      this.$emit('force-update');
    }
  }
}

// 父组件
<template>
  <div>
    <child-component :count="count" @force-update="forceUpdate"></child-component>
  </div>
</template>

export default {
  data() {
    return {
      count: 0
    };
  },
  methods: {
    forceUpdate() {
      this.$forceUpdate();
    }
  }
}

In this example, the subcomponent triggers a custom event named force-update through the $emit method. In the parent component, we use @force-update to listen to this event on the child component, and call the $forceUpdate method in the callback function to update the view of the parent component.

It should be noted that using the $forceUpdate method may cause performance issues and complications. So we should try to avoid using it, but automatically trigger updates by modifying data, or use elastic data to achieve better performance and maintainability.

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