How to find the location in vue (three methods)

Vue is a popular JavaScript framework that is widely used to build web applications. In Vue, there are many methods that can be used to find the position. This article will introduce the three main location lookup methods in Vue and their uses.

1. refs

In Vue, each component can have a unique ref attribute through which the component instance can be accessed. The location of a component can be easily found using the ref attribute.

<template>
  <div>
    <child-component ref="myChildComponent"></child-component>
  </div>
</template>
<script>
  import ChildComponent from './components/ChildComponent.vue'

  export default {
    components: { ChildComponent },
    mounted() {
      const myChildComponent = this.$refs.myChildComponent
      console.log(myChildComponent.$el)
    }
  }
</script>

In the above example, we can access the instance of the child component (ChildComponent) through the ref attribute and use the $el attribute to access its DOM element. This method is very convenient, especially when you need to perform some DOM operations on the child component in the parent component.

It should be noted that when using refs, the component must have been rendered and the DOM element must exist. Otherwise, undefined errors may occur.

2. this.$root.$el

The Vue component hierarchy is usually tree-shaped, and each component has a parent property pointing to its parent component until the root (root) components. Through the $root property of the component instance, we can access the root component of the Vue application and use its $el property to access the DOM element.

<template>
  <div>
    <button @click="scrollToFooter">Go to Footer</button>
    <div class="content"></div>
    <footer ref="myFooter"></footer>
  </div>
</template>
<script>
  export default {
    methods: {
      scrollToFooter() {
        const el = this.$root.$el.querySelector('.my-footer')
        window.scrollTo({ top: el.offsetTop, behavior: 'smooth' })
      }
    }
  }
</script>

In the above example, we can use $root.$el in the method to access the DOM element, and use the offsetTop attribute to get the position of the element in the document. This method is very useful, especially when you need to scroll from one component to another.

It should be noted that when using $root.$el, the element must exist in the template of the root component. Otherwise, undefined errors may occur.

3. computed

Computed properties are another very useful feature in Vue. Computed properties allow us to calculate new values ​​based on the component's state. Computed properties themselves do not modify any data, but depend on other data and return a new calculated result.

<template>
  <div>
    <h1>{{ pageTitle }}</h1>
    <div class="content"></div>
    <footer></footer>
  </div>
</template>
<script>
  export default {
    data() {
      return {
        title: 'My App'
      }
    },
    computed: {
      pageTitle() {
        return `${this.title} - My App`
      }
    }
  }
</script>

In the above example, we use the calculated property (pageTitle) to calculate the page title. When the title attribute changes, the pageTitle attribute will be automatically updated.

It should be noted that using calculated properties is very useful for handling simple logic. However, if a computed property requires complex calculations, performance may be affected. At this point, a better approach is to use a watcher.

Through these three methods, we can easily find the location in the Vue component and perform some operations, such as accessing DOM elements, scrolling windows, etc. Although each method has its scope, different methods may be used in specific situations.

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