When should vue add ref?

Vue is a popular JavaScript framework widely used for front-end development. In Vue, ref is a very useful directive that can be used to access a reference to a specific component or element. So, when do you need to use ref in Vue?

In Vue, the ref directive is usually used in the following scenarios:

1. Access child components

When you need to access the properties and methods of the child component through the instance of the parent component , the ref directive is essential. By using the ref directive, you can create a reference to the child component and then use the $refs attribute in the parent component to access the child component. For example, assuming you have a child component called ChildComponent, you can use the following code in the parent component template to create a reference:

<template>
  <child-component ref="childComponent"></child-component>
</template>

Then, you can access the child component using the following code in the parent component ：

this.$refs.childComponent.methodName();

Among them, methodName is the method name defined in the subcomponent.

2. Access DOM elements

In some cases, you may need to access DOM elements directly, such as using a third-party library in a Vue component, or need to get a specific element in a Vue component properties. For these situations, the ref directive is also very useful. For example, if you need to get the value attribute of a specific element, you can use the following code in the template:

<template>
  <input ref="myInput" type="text" />
</template>

Then, you can use the following code in the Vue component to get the value attribute of the element:

const value = this.$refs.myInput.value;

3. Access the instance object

Sometimes, you may need to access the instance object itself in a Vue component, such as when you need to use a specific Vue API. In this case, the ref directive can help you access the Vue instance object conveniently. For example, if you need to use the $emit method in a Vue component to trigger an event, you can use the following code:

<template>
  <button @click="emitEvent">Click me</button>
</template>

<script>
  export default {
    methods: {
      emitEvent() {
        this.$emit('myEvent');
      }
    },
    mounted() {
      this.$refs.myComponent.$on('myEvent', () => {
         // Event triggered
      });
    }
  }
</script>

In this case, you can use the following code in the template to create a reference to the Vue instance:

<child-component ref="myComponent"></child-component>

Then, in the mounted hook function, you can use the following code to access the Vue instance:

this.$refs.myComponent.$on('myEvent', () => {
   // Event triggered
});

In short, the ref directive is very useful in Vue and can help you access subcomponents, More convenient when working with DOM elements and Vue instances. However, it should be noted that you should avoid abusing the ref directive as much as possible. If possible, please use Vue's data binding and event mechanism and other functions, which is more in line with Vue's design ideas.

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