[Vuejs]-Vue.js – created() for dynamic drop-down

You just have to move your getSections() function after you fetched your departmens inside getDepartments method. see code below

created() {
   this.getDepartments()
}

then in your getDepartments function call the function getSections, like this

methods: {
    getDepartments() {
       axios.get('/getDepartments').then(({data}) => {
            this.getSections()
        })
    } 
}