[Vuejs]-Can't get json array into js array on created

looks like you try to call a jquery-method inside your vue-app, but jquery ($) is not into your project/scope. try to do it a) with jquery included (not recommended, much bloat just for one function call) or with plain js.

you might want to look into a more lightweight framework for ajax calls like axios.

edit: or, as the comment states, the built-in fetch method of modern browsers.