How can I call a statement or method after the loop complete on vue component?

Question

My vue component like this :

<template>
    <div class="row">
        <div class="col-md-3" v-for="item in items">
            ...
        </div>
    </div>
</template>
<script>
    export default {
        ...
        computed: {
            items() {
                ...
            }
        },
        ...
    }
</script>

If the loop complete, I want to call a statement or method

So the statement is executed when the loop completes

How can I do it?

Update :

From Kira San answer, I try like this :

  <template>
        <div class="row">
            <div class="col-md-3" v-for="(item, key) in items" v-for-callback="{key: key, array: items, callback: callback}">
                ...
            </div>
        </div>
    </template>
    <script>
        export default {
            ...
            computed: {
                items() {
                    const n = ...
                    return n
                }
            },
            directives: {
              forCallback(el, binding) {
                  let element = binding.value
                  if (element.key == element.array.length - 1)
                  if (typeof element.callback === 'function') {
                    element.callback()
                  }
                }
            },
            methods: {
                callback() {
                    console.log('v-for loop finished')          
                }
            }
        }
    </script>

The console log not display

My items is object

If do console.log(n) in items, the result like this :

Answer 1

Look at this example.

new Vue({
  el: '#app',

  computed: {
    items() {
      return {item1: 'value1', item2: 'value2'}
    }
  },

  methods: {
    callback() {
      console.log('v-for loop finished')
    }
  },

  directives: {
    forCallback(el, binding) {
      let element = binding.value
      var key = element.key
      var len = 0

      if (Array.isArray(element.array)) {
        len = element.array.length
      }

      else if (typeof element.array === 'object') {
        var keys = Object.keys(element.array)
        key = keys.indexOf(key)
        len = keys.length
      }

      if (key == len - 1) {
        if (typeof element.callback === 'function') {
          element.callback()
        }
      }
    }
  },

})

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.3.4/vue.min.js"></script>

<div id="app">
    <div class="row">
        <div class="col-md-3" v-for="(item, key) in items" v-for-callback="{key: key, array: items, callback: callback}">
            ...
        </div>
    </div>
</div>

Answer 2

You can do with an if inside the loop, like this:

<template>
    <div class="row">
        <div class="col-md-3" v-for="(item, index in items)">
            <div v-if="index === items.length -1">
                Display what ever you want here 
            <\div>
        </div>
    </div>
</template>

Or if you want to do something in js then call a function when the same condition is true, like this:

 <div class="col-md-3" v-for="(item, index in items)">
            <div v-if="index === items.length -1 && lastIteration()">
                Display what ever you want here 
            <\div>
        </div>

methods: {
  lastIteration() {
     alert("last");
}
}

I didn't test it but the ideea is good and it should work. Hope to answer your question :)

Answer 3

You can accomplish that with a directive.

Example usage:

<div class="col-md-3" v-for="(item, key) in items" v-for-callback="{key: key, array: items, callback: callback}">
  <!--content-->
</div>

Create a new directive for-callback which will keep track of the elements that was rendered with v-for. It will basically check if the current key is the end of the array. If so, it will execute a callback function that you provide.

Vue.directive('for-callback', function(el, binding) {
  let element = binding.value
  if (element.key == element.array.length - 1)
    if (typeof element.callback === 'function') {
      element.callback()
    }
})

Or if you don't want to define it globally. Add this to your component options instead:

directives: {
  forCallback(el, binding) {
      let element = binding.value
      if (element.key == element.array.length - 1)
      if (typeof element.callback === 'function') {
        element.callback()
      }
    }
}

v-for-callback expects an options object.

{
  key: key, // this will contain the item key that was generated with `v-for`
  array: items, // the actual `v-for` array
  callback: callback // your callback function (in this example, it's defined in the component methods
}

Then in your component options:

methods: {
    callback() {
        console.log('v-for loop finished')          
    }
}