Invoke a function within a v-if directive in a Vue.js script

Question

Invoke a function within a v-if directive in a Vue.js script

I'm relatively new to working with vue.js and I have a small issue that I need help with.

Within my vue.js file, there is an existing method called doSomething():

doSomething(){
   //updates few properties here
}

I also have a list or array as a computed property, let's call it pageUser(), and I want to trigger the doSomething() method whenever pageUser.length == 0.

How can this be achieved in vue.js? Is using v-if in a tag a valid approach to invoke the method, or are there other methods to accomplish this?

javascript typescript vue.js vuejs2 vue-component

Answer 1

Answer №1

To make your method trigger in a computed property:

const app = Vue.createApp({
  data() {
    return {
      user: [{id: 1}, {id: 2}],
    };
  },
  computed: {
    pageUser() {
      if (this.user.length) return this.user 
      this.doSomething()
      return 'no user'
    }
  },
  methods: {
    doSomething() {
      console.log('done something')
    },
    empty() {
      this.user = []
    }
  }
})
app.mount('#demo')

<script src="https://unpkg.com/vue@3/dist/vue.global.prod.js"></script>
<div id="demo">
  <button @click="empty">empty</button>
  <div>{{ pageUser }}</div>
</div>

Answer 2

To make your method trigger in a computed property:

const app = Vue.createApp({
  data() {
    return {
      user: [{id: 1}, {id: 2}],
    };
  },
  computed: {
    pageUser() {
      if (this.user.length) return this.user 
      this.doSomething()
      return 'no user'
    }
  },
  methods: {
    doSomething() {
      console.log('done something')
    },
    empty() {
      this.user = []
    }
  }
})
app.mount('#demo')

<script src="https://unpkg.com/vue@3/dist/vue.global.prod.js"></script>
<div id="demo">
  <button @click="empty">empty</button>
  <div>{{ pageUser }}</div>
</div>

Answer 3

Answer №2

It is important to ensure that computed properties do not have any side effects. The solution for what you are trying to achieve is using a watcher. By watching your computed list, you can trigger a method when it becomes empty.

watch(pageUsers, () => {
    if(pageUsers.length === 0) {
        doSomething();
    }
})

Answer 4

It is important to ensure that computed properties do not have any side effects. The solution for what you are trying to achieve is using a watcher. By watching your computed list, you can trigger a method when it becomes empty.

watch(pageUsers, () => {
    if(pageUsers.length === 0) {
        doSomething();
    }
})

Invoke a function within a v-if directive in a Vue.js script

Answer №1

Answer №2

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