The progress of Vue3 compared to Vue2: more flexible custom instructions

The progress of Vue3 compared to Vue2: more flexible custom instructions

With the continuous development of front-end technology, Vue.js, as a popular JavaScript framework, continues to launch new versions to satisfy developers needs. One of the improvements of Vue3 over Vue2 is that it provides more flexible capabilities in custom instructions. This article will explain this improvement in detail in the form of introducing new features and code examples of Vue3.

In Vue2, custom directives are created and used through global registration or local registration. The process of creating a custom instruction is relatively simple, but it is difficult to meet the needs in some complex scenarios. Vue3 implements fine-grained control of custom directives by using the app.directive method.

First, let’s look at a simple custom instruction example in Vue2:

<template>
  <div>
    <input v-focus />
  </div>
</template>

<script>
export default {
  directives: {
    focus: {
      inserted: function (el) {
        el.focus()
      }
    }
  }
}
</script>

In this example, we have customized a instruction v-focus. When When this element is inserted into the DOM, it automatically gets focus. In Vue2, directives are registered globally through the directives option.

In Vue3, we can create and register custom instructions through the app.directive method. Next is an example of using a custom directive from Vue3:

<template>
  <div>
    <input v-focus />
  </div>
</template>

<script>
import { createApp } from 'vue'

const app = createApp()

app.directive('focus', {
  beforeMount(el) {
    el.focus()
  }
})

export default {
  mounted() {
    app.mount('#app')
  }
}
</script>

In Vue3, we use the app.directive method to create a custom directive and add it in beforeMountThe behavior of the directive defined in the hook. In the above example, we mount the Vue application to the specified DOM through app.mount('#app').

In addition to a more flexible way to register custom instructions, Vue3 also provides more options for instruction hook functions so that developers can better control the life cycle of instructions. The following are the command hook functions that can be used in Vue3:

• beforeMount: Called before the element is mounted to the DOM;
• mounted : Called after the element is mounted to the DOM;
• beforeUpdate: Called before the element is updated;
• updated: Called after the element is updated;
• beforeUnmount: Called before the element is unmounted from the DOM;
• unmounted: Called after the element is unmounted from the DOM.

Through these hook functions, we can better control the behavior of custom instructions.

In summary, Vue3 provides more flexible capabilities in custom instructions compared to Vue2. By using the app.directive method and more instruction hook functions, we can better control the life cycle of instructions and meet the needs of more complex scenarios. Therefore, if you need more flexible custom instructions when using Vue to develop projects, you can consider upgrading to Vue3 to experience these powerful features.

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