when trying to call a JavaScript function from an imported helper class in my Vue.js component. I import my helper class in my component and try to use mounted() to call it and pass a paramter to the helper class.

I tried out some solutions from here, but didn’t help:
Vue.js: Import class with function and call it in child component

https://forum.vuejs.org/t/how-to-use-helper-functions-for-imported-modules-in-vuejs-vue-template/6266

This is what I tried so far, any ideas?

there is a helper class myHelper.js:

export default myHelper {
myHelperFunction(param) {
return param;
}
}

there is a vue.js component MyComponent.vue:

<template>
<v-text-field :rules=”[myRule]“></v-text-field>
</template>

<script>
import myHelper from ‘./myHelper.js’;

export default {
name: ‘MyComponent’,
data() {
return {
myCls: new myHelper(),
myRule: this.callHelperFunction,
};
},
components: {
myHelper,
},
mounted() {
this.myCls.myHelperFunction();
},
methods: {
callHelperFunction(param) {
this.myCls.myHelperFunction(param);
}
},
};
</script>

Solution :

You are not really exporting the class. It is a plain object. To export a class instead of an object do this:

// Notice the use of class keyword
export default class MyHelper {
myHelperFunction(param) {
return param;
}
}

Also, you do not need:

components: {
myHelper,
},

Rest of the code stays the same.