feat: add CancelToken and isCancel to axios instance (#292)

Author: 3b3ziz

docs/usage.md

@@ -35,3 +35,53 @@ methods: {
   }
 }
 ```
+
+### Cancel token
+
+You can cancel a request using a _cancel token_.
+
+> The axios cancel token API is based on the withdrawn [cancelable promises proposal](https://github.com/tc39/proposal-cancelable-promises).
+
+You can create a cancel token using the `CancelToken.source` factory as shown below:
+
+```js
+const source = this.$axios.CancelToken.source()
+
+this.$axios.$get('/user/12345', {
+  cancelToken: source.token
+}).catch(error => {
+  if (this.$axios.isCancel(error)) {
+    console.log('Request canceled', error)
+  } else {
+    // handle error
+  }
+})
+
+this.$axios.$post('/user/12345', {
+  name: 'new name'
+}, {
+  cancelToken: source.token
+})
+
+// cancel the request (the message parameter is optional)
+source.cancel('Operation canceled by the user.')
+```
+
+You can also create a cancel token by passing an executor function to the `CancelToken` constructor:
+
+```js
+const { CancelToken } = this.$axios
+let cancel
+
+this.$axios.$get('/user/12345', {
+  cancelToken: new CancelToken(c => {
+    // An executor function receives a cancel function as a parameter
+    cancel = c
+  }),
+})
+
+// cancel the request
+cancel()
+```
+
+> Note: you can cancel several requests with the same cancel token.

lib/plugin.js

@@ -184,6 +184,8 @@ export default (ctx, inject) => {
 
   // Create new axios instance
   const axios = Axios.create(axiosOptions)
+  axios.CancelToken = Axios.CancelToken
+  axios.isCancel = Axios.isCancel
 
   // Extend axios proto
   extendAxiosInstance(axios)