1, commonfun.js:
export default {

va:{
    "000": "0",
    "001": "1",
    "002": "2"
    
},
func:(retcode)=>{
    console.log(this);
    return this.va[retcode];
}

}
2, main.js:
import vue related dependencies
import commonfun from commonfun
Vue.prototype.$utils=commonfun;

3. A component in the application, login.vue:
export default {
.

methods:{
    login(){
        this.$utils.func("001")
    }
}

}
when login calls func, there is an error executing return. Why, cannot read property "001"of undefined; prints out this objects are all nested in a property. Unknown reasons are as follows:
{

a:{
   va:  Object,
   func: function..
}

}
modify commonfun.js "s func function return this.a.va [retcode] can return normally; do not know the origin of a?