`Vue function is unable to find the definition of a variable`

I am struggling with utilizing a variable in a vue 3 application that has been emitted by a component called Mags. The variable is functioning properly in the importMags function, however, I am unable to access it within the handleSubmit function. It consistently returns as null.

<template>
    <form @submit.prevent="handleSubmit">
      <Mags name="magResults"  
      @selectedtags="importMags"> </Mags>
      <q-btn label="Submit" type="submit"  />
    </form>
</template>
<script>
import { ref } from "vue";
export default {
  name: "Name",
 components: { Mags },
  setup() {
    function handleSubmit() {
    console.log(nowMags);
    }

    function importMags(selectedMags) {
      let nowMags = selectedMags;
      return nowMags;
    }
    return {
      importMags,
      nowMags: ref(null),
      selectedMags: ref(null),
    
    };
  },
};
</script>

Answer №1

There seem to be a couple of issues within your code snippet.

<form @submit.prevent="handleSubmit">

Based on this line, the handleSubmit() function is expected to be called, however, it is not referenced in the setup() function. Although the function is defined, it also needs to be returned.

Additionally, you should initialize nowMags at the start of the setup() function as follows:

const nowMags = ref(null)

To read or set the value of nowMags in any function, you must use nowMags.value = x, x = nowMags.value, or console.log(nowMags.value).

Below is a revised code snippet that may help clarify things for you.

setup() {
    // Define data variables here
    const nowMags = ref(null)
    const selectedMags = ref(null)
     
    // Define functions here
    const handleSubmit = () => {
      console.log(nowMags.value)
    }
    const importMags(selectedMags) {
      nowMags.value = selectedMags
      return nowMags.value
    }
    
    return {
      nowMags,
      selectedMags,
      importMags,
      handleSubmit
    }
 };

Answer №2

The variable nowMags was initially declared within the scope of the importMags() function in your code snippet. If you intend for this variable to be accessible outside of the function, you should consider moving its declaration to a higher scope.

 components: { Mags },
  setup() {
    let nowMags; // It might be useful to assign an initial value here

    function handleSubmit() {
        console.log(nowMags);
    }

    function importMags(selectedMags) {
      nowMags = selectedMags;
      return nowMags;
    }
    
    return {
      importMags,
      nowMags: ref(null),
      selectedMags: ref(null),
    };
  },

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