Ways to access a conditional rendered ref element in Vue using v-if

Question

Ways to access a conditional rendered ref element in Vue using v-if

I have a specific element that is conditionally rendered using v-if="isLogged" when a user is logged in:

<div
  v-if="isLogged"
  class="chatBlock"
  ref="chat"
></div>

The issue I'm facing is trying to retrieve the scroll height of the chat reference within the mounted() function - specifically using this.$refs.logged.scrollHeight. However, this proves to be challenging because if a user is not logged in, the div will not be rendered during the mounting stage. Consequently, even if a user logs in afterward, it won't work as the mounted stage has already passed.

Is there a way to monitor the appearance of an element in the DOM by utilizing the watch method?

UPDATE

In response to Steven's suggestion below, I have incorporated a watcher in the mounted():

this.$store.watch(
  (state) => {
    return this.$store.getters.isLogged
  },
  (newValue, oldValue) => {
    if (newValue) {
      this.chatHeight = this.$refs.chat.scrollHeight
    }
  }
)

javascript vue.js

Answer 1

Answer №1

The solution provided did not work in my case as the watch function does not ensure that the element is already rendered on the DOM.

In order to ensure that the element is available, I had to implement the use of $nextTick

 if (newValue) {   
     this.$nextTick(function () {
         this.chatHeight = this.$refs.chat.scrollHeight
    })
}

This will ensure that the code is executed after the next DOM update cycle.

Answer 2

The solution provided did not work in my case as the watch function does not ensure that the element is already rendered on the DOM.

In order to ensure that the element is available, I had to implement the use of $nextTick

 if (newValue) {   
     this.$nextTick(function () {
         this.chatHeight = this.$refs.chat.scrollHeight
    })
}

This will ensure that the code is executed after the next DOM update cycle.

Answer 3

Answer №2

To implement a watch feature for isLogged, you need to add logic to retrieve your chat reference when it is active. It's important to include a check on whether your component is mounted and organize your logic in a centralized function.

Here's how you can set up your component:

const componentOptions = {
  methods: {
    checkChat() {
      const chatRef = this.$refs.chat
      if (chatRef) {
        // Add your code here...
      }
    }
  },
  mounted() {
    this.checkChat();
  },
  watch: {
    isLogged(value) {
      if (value) {
        this.checkChat();
      }
    }
  }
}

—-

Alternatively, you can utilize v-show instead of v-if to render the element while keeping it hidden when necessary.

Answer 4

To implement a watch feature for isLogged, you need to add logic to retrieve your chat reference when it is active. It's important to include a check on whether your component is mounted and organize your logic in a centralized function.

Here's how you can set up your component:

const componentOptions = {
  methods: {
    checkChat() {
      const chatRef = this.$refs.chat
      if (chatRef) {
        // Add your code here...
      }
    }
  },
  mounted() {
    this.checkChat();
  },
  watch: {
    isLogged(value) {
      if (value) {
        this.checkChat();
      }
    }
  }
}

—-

Alternatively, you can utilize v-show instead of v-if to render the element while keeping it hidden when necessary.

Answer 5

Answer №3

After following Steven's advice, I decided to switch to v-show, which ended up being the perfect solution for my situation. Using v-show proved to be a more efficient choice compared to v-if because of its cost-effective toggling capabilities. If you're curious about the differences, check out this insightful answer:

Answer 6

After following Steven's advice, I decided to switch to v-show, which ended up being the perfect solution for my situation. Using v-show proved to be a more efficient choice compared to v-if because of its cost-effective toggling capabilities. If you're curious about the differences, check out this insightful answer:

Answer 7

Answer №4

Consider implementing a nextTick around the call to the ref. By doing this, the ref will be available when the code is executed within the block.

Check out this demonstration:

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/3.4.8/vue.global.min.js"></script>

<div id="app">
  <div>
    <button @click="handleToggle" style="margin-right:0.5rem;">Toggle</button>
    <my-element v-if="visible" ref="myElement" />
  </div>
</div>

<script>
  const {
    createApp
  } = Vue

  createApp({
    components: {
      myElement: {
        template: "<span>{{ text }}</span>",
        data() {
          return {
            text: '',
          };
        },
      }
    },
    data() {
      return {
        visible: false,
      }
    },
    methods: {
      handleToggle() {
        this.visible = !this.visible;

        if (this.visible) {
          this.$nextTick(() => {
            this.$refs.myElement.text = "I'm visible";
          });
        }
      },
    }
  }).mount('#app')
</script>

Answer 8

Consider implementing a nextTick around the call to the ref. By doing this, the ref will be available when the code is executed within the block.

Check out this demonstration:

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/3.4.8/vue.global.min.js"></script>

<div id="app">
  <div>
    <button @click="handleToggle" style="margin-right:0.5rem;">Toggle</button>
    <my-element v-if="visible" ref="myElement" />
  </div>
</div>

<script>
  const {
    createApp
  } = Vue

  createApp({
    components: {
      myElement: {
        template: "<span>{{ text }}</span>",
        data() {
          return {
            text: '',
          };
        },
      }
    },
    data() {
      return {
        visible: false,
      }
    },
    methods: {
      handleToggle() {
        this.visible = !this.visible;

        if (this.visible) {
          this.$nextTick(() => {
            this.$refs.myElement.text = "I'm visible";
          });
        }
      },
    }
  }).mount('#app')
</script>

Ways to access a conditional rendered ref element in Vue using v-if

Answer №1

Answer №2

Answer №3

Answer №4

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