Quite a few frameworks have built-in HTTP APIs. Angular 2 has the http module, JQuery has $.ajax, and, up until Vue 2.0, Vue.js had vue-resource. In Vue 2.0, the developers decided that having a built-in http client module was rather redundant, and could be better serviced by third-party libraries. The alternative most frequently recommended is Axios.
Axios is a great http client library. It uses promises by default and runs on both the client and the server (which makes it appropriate for fetching data during server-side rendering). It’s also quite easy to use with Vue. Because it uses promises, you can combine it with async/await to get an amazingly concise and easy-to-use API, as I will demonstrate here.
Installation
Axios should be installed from NPM or Yarn:
# Yarn
$ yarn add axios
# NPM
$ npm install axios --save
Populating Data with a GET Request
While it’s generally poor practice, you can use Axios directly in your components to fetch data from a method, lifecycle hook, or whenever.
ExampleComponent.vue
<template>
<ul v-if="posts && posts.length">
<li v-for="post of posts">
<p><strong>{{post.title}}</strong></p>
<p>{{post.body}}</p>
</li>
</ul>
<ul v-if="errors && errors.length">
<li v-for="error of errors">
{{error.message}}
</li>
</ul>
</template>
<script>
import axios from 'axios';
export default {
data() {
return {
posts: [],
errors: []
}
},
// Fetches posts when the component is created.
created() {
axios.get(`http://jsonplaceholder.typicode.com/posts`)
.then(response => {
// JSON responses are automatically parsed.
this.posts = response.data
})
.catch(e => {
this.errors.push(e)
})
// async / await version (created() becomes async created())
//
// try {
// const response = await axios.get(`http://jsonplaceholder.typicode.com/posts`)
// this.posts = response.data
// } catch (e) {
// this.errors.push(e)
// }
}
}
</script>
Pushing Data with a POST Request
One can send POST, PUT, PATCH, and DELETE requests just as easily.
(Note, it’s a terrible idea to send requests on every input event, at the very least do some throttling or debouncing.)
ExampleComponent.vue
<template>
<input type="text" v-model="postBody" @change="postPost()"/>
<ul v-if="errors && errors.length">
<li v-for="error of errors">
{{error.message}}
</li>
</ul>
</template>
<script>
import axios from 'axios';
export default {
data() {
return {
postBody: '',
errors: []
}
},
// Pushes posts to the server when called.
postPost() {
axios.post(`http://jsonplaceholder.typicode.com/posts`, {
body: this.postBody
})
.then(response => {})
.catch(e => {
this.errors.push(e)
})
// async / await version (postPost() becomes async postPost())
//
// try {
// await axios.post(`http://jsonplaceholder.typicode.com/posts`, {
// body: this.postBody
// })
// } catch (e) {
// this.errors.push(e)
// }
}
}
</script>
A Common Base Instance
A frequently overlooked but very useful capability Axios provides is the ability to create a base instance that allows you to share a common base URL and configuration across all calls to the instance. This comes in handy if all of your calls are to a particular server, or need to share headers, such as an authorization header.
http-common.js
import axios from 'axios';
export const HTTP = axios.create({
baseURL: `http://jsonplaceholder.typicode.com/`,
headers: {
Authorization: 'Bearer {token}'
}
})
You could now use HTTP like so,
<script>
import {HTTP} from './http-common';
export default {
data() {
return {
posts: [],
errors: []
}
},
created() {
HTTP.get(`posts`)
.then(response => {
this.posts = response.data
})
.catch(e => {
this.errors.push(e)
})
}
}
</script>
Reference
That’s just scratching the surface of what Axios can do. See the GitHub repository for more information and documentation.