why setup run twice in vue2

[zhoufanglu]

i install @vue/composition-api at vue 2.6。

• in setup

  <script>
  export default {
  setup() {  // run twice
  console.log('test composition =================')
  }
  }
  </script>

• in created

  created() {  // run  at a time
  console.log('test composition =================')
  }

[xiaoxiangmoe]

Can you provide me a reproduction demo?

[zhoufanglu]

Can you provide me a reproduction demo?

sorry, this is company project, rather old, later i use vue2 syntax

[alexdeia]

I have the same problem with vue 2 and composition api. But in onMounted hook code runs once.

[houcheng]

Is there any progress on this issue? For reproducing, Just create a vue 2 project and write a component in composition API. The setup would be called twice. Below is a simple vue for reproducing this issue:

<script setup lang="ts">
import {ref} from "@vue/composition-api";

const a = ref('aa')
const b = ref('bb')
console.log('call setup')
</script>

<template lang="pug">
span haha {{a}} {{b}}
</template>

[spart4k]

hey?

[marcel-wtfoxtrot]

Hey @xiaoxiangmoe ,

i just ran into the exact same issue using vue 2.7.14 and composition-api@1.7.2

here is a Reproduction Demo: https://codesandbox.io/s/confident-architecture-p6jm5p?file=/src/App.vue

Just have a look at the terminal. You'll find Setup being printed twice, mounted only once.

[xiaoxiangmoe]

Hi，@marcel-wtfoxtrot In vue 2.7, you needn't use composition-api, just use vue

[wsxiao]

Have you found the reason?