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API service

API service abstraction

To make calls to the backend, it is convenient to separate the code related to the transport layer (forming and sending a request) into a separate js module.

Then in your component access to your backend will look like this:

import { api } from "@/services/api";

// loading.value = true;
const userData = await api.users.getUserData({ userId });
// loading.value = false;

All the complexity of backend communication is hidden in the api module.

Example api.js:

import auth from "./auth";
import users from "./users";
import utils from "./utils";
import products from "./products";
import { authInterceptor, notificationInterceptor } from "./interceptors";
import http from "./http";
import { useAuth } from "@/user-account/composables/useAuth";

const api = {
  init() {
    // to set token into every request

export { api };
export default api;

Example users.js

import http from "./http";

const users = {
  async getUserData(params) {
    return await http.get("/api/users/user", params);

http.js is a wrapper around requests to the server via your favorite library.

What is the convenience of abstracting the backend communication code from the main application code into a separate service?

You can easily replace axios with fetch or XHR, REST with JSON-RPC or WebSockets. The code in the components does not change and remains simple and explicit.

Where to do API requests from?

What is the best place in the component to request for data on the backend API - in the body of the script setup, or in the onMounted hook?

In onMounted.

  1. You can't safely use await in the body of the script setup, it requires Suspense and makes the component asynchronous and unnecessarily complicates the application. So you have to use promise then or IIFE , which is much worse to read and less convenient.

  2. If there is an uncaught error in the request, it cannot be handled in script setup, unlike the hook.

  3. From the point of view of system design, script setup is a component constructor. It is illogical to request data from external sources in it.

  4. There was repeated evidence that requests for data in script setup did not work correctly, but when moved to onMounted they worked. Depends on the context, but nevertheless.