VueJS accessing externaly imported method in vue component

1. You can call the imported something function under any lifecycle method you want. Here, I'd recommend using the mounted method. That triggers once all of the component's HTML has rendered.

2. You can add the something function under the vue component's methods, then call the function directly from the template.

<template>
    <div>
        <button type="button" name="button" @click="something">
            Call External JS
        </button>
        <div id="demo"></div>
    </div>
</template>

<script>
import something from "./something.js"

export default {
    mounted() {
        something()
    },
    methods: {
        something,
    },
}
</script>

A better solution would be to to use mixins:

import something from './something.js'
export default {
  mixins: [something]
}

now you can use whatever methods / computed you have exported in something.js, directly on this.

So, in your example, you have myFun() exported from something.js, and we can call it from Dashboard.vue like so:

<template>
    <div>
        <button type="button" name="button" @click="myFun">Call External JS</button>
        <div id="demo"></div>
    </div>
</template>

<script>
    import something from "./something.js"
    export default {
        mixins: [something],
        mounted(){
            this.myFun()
        }
    }
</script>

I hope I got the syntax right, but that's generally the idea of mixins.