Making axios global in Vue project is not working

Question

Until now, I had been importing axios in each Vue component where I wanted to make HTTP requests, like this.

<script lang="ts">
import axios from 'axios';

@Component
export default class ExamplePage extends Vue {
  created(): void {
    axios.post(some_path);
  }
}

However, now I want to define a global interceptor for all axios requests, basically to catch all 401 unauthorized responses from the backend server (Rails) and log out the user. My understanding so far is that you must instantiate axios once and use it everywhere, instead of importing and using a different instance in each file.

I've referred to this and this, and tried the below.

// application.js

import '../assets/sass/base.sass';
import App from '../app';
import Vue from 'vue';
import VueRouter from 'vue-router';
import axios from 'axios';
import router from '../routes';

Vue.use(VueRouter);

document.addEventListener('DOMContentLoaded', () => {
  new Vue({
    el: '#application',
    router,
    render: (h) => h(App),
  });
});

axios.interceptors.response.use(
  response => response,
  error => {
    const status = error.response;
    if(status === 401) {
      // do stuff
    }
  }
);

Vue.prototype.$http = axios

When I tried to call this.$http.put(...) in another file, it said property $http doesn't exist (I'm guessing it's because this in the context of that component is the component itself, but I'm not sure). How can I fix this?

[UPDATE] Thanks to the responses, I decided to initialize an axios instance in a separate file and then use that instead. However, this is still not working. The 401 responses don't seem to be triggering the interceptor at all.

Is there some additional configuration necessary?

// axios-instance.ts
import axios, { AxiosInstance } from 'axios';

const axiosInstance: AxiosInstance = axios.create();

axiosInstance.interceptors.response.use(
  response => response.data,
  async function(error) {
    console.log("THIS IS THE 401 INTERCEPTOR")
    const status = error.response;
    if(status === 401) {
      // Log out user
    }
  }
);

export default axiosInstance;

// Some component
<script lang="ts">
import axiosInstance from 'axios-instance';

@Component
export default class ExamplePage extends Vue {
  created(): void {
    axiosInstance.post(some_path);
  }
}

Answer 1

Doesn't solve your question directly, but the way I create instance of axios is:

// axios-instance.js

import axios from 'axios'

const instance = axios.create({
  baseURL: 'https://some-domain.com/api/',
  timeout: 1000,
  headers: {'X-Custom-Header': 'foobar'}
});

export default instance

After you just import the instance

// application.js

import axios from '../../axios-instance'