Adding axios.isCancel method

README.md

@@ -471,14 +471,13 @@ You can cancel a request using a *cancel token*.
 You can create a cancel token using the `CancelToken.source` factory as shown below:
 
 ```js
-var Cancel = axios.Cancel;
 var CancelToken = axios.CancelToken;
 var source = CancelToken.source();
 
 axios.get('/user/12345', {
   cancelToken: source.token
 }).catch(function(thrown) {
-  if (thrown instanceof Cancel) {
+  if (axios.isCancel(thrown)) {
     console.log('Request canceled', thrown.message);
   } else {
     // handle error

axios.d.ts

@@ -120,7 +120,8 @@ export interface AxiosStatic extends AxiosInstance {
   (url: string, config?: AxiosRequestConfig): AxiosPromise;
   create(config?: AxiosRequestConfig): AxiosInstance;
   Cancel: CancelStatic;
-  CancelToken: CancelTokenStatic; 
+  CancelToken: CancelTokenStatic;
+  isCancel(value: any): boolean;
   all<T>(values: (T | Promise<T>)[]): Promise<T[]>;
   spread<T, R>(callback: (...args: T[]) => R): (array: T[]) => R;
 }

lib/axios.js

@@ -37,6 +37,7 @@ axios.create = function create(defaultConfig) {
 // Expose Cancel & CancelToken
 axios.Cancel = require('./cancel/Cancel');
 axios.CancelToken = require('./cancel/CancelToken');
+axios.isCancel = require('./cancel/isCancel');
 
 // Expose all/spread
 axios.all = function all(promises) {

lib/cancel/Cancel.js

@@ -14,4 +14,6 @@ Cancel.prototype.toString = function toString() {
   return 'Cancel' + (this.message ? ': ' + this.message : '');
 };
 
+Cancel.prototype.__CANCEL__ = true;
+
 module.exports = Cancel;

lib/cancel/isCancel.js

@@ -0,0 +1,5 @@
+'use strict';
+
+module.exports = function isCancel(value) {
+  return !!(value && value.__CANCEL__);
+};

test/specs/api.spec.js

@@ -34,6 +34,12 @@ describe('static api', function () {
   it('should have factory method', function () {
     expect(typeof axios.create).toEqual('function');
   });
+
+  it('should have Cancel, CancelToken, and isCancel properties', function () {
+    expect(typeof axios.Cancel).toEqual('function');
+    expect(typeof axios.CancelToken).toEqual('function');
+    expect(typeof axios.isCancel).toEqual('function');
+  });
 });
 
 describe('instance api', function () {

test/specs/cancel/isCancel.spec.js

@@ -0,0 +1,12 @@
+var isCancel = require('../../../lib/cancel/isCancel');
+var Cancel = require('../../../lib/cancel/Cancel');
+
+describe('isCancel', function() {
+  it('returns true if value is a Cancel', function() {
+    expect(isCancel(new Cancel())).toBe(true);
+  });
+
+  it('returns false if value is not a Cancel', function() {
+    expect(isCancel({ foo: 'bar' })).toBe(false);
+  });
+});

test/specs/instance.spec.js

@@ -16,6 +16,7 @@ describe('instance', function () {
         'create',
         'Cancel',
         'CancelToken',
+        'isCancel',
         'all',
         'spread',
         'default'].indexOf(prop) > -1) {

test/typescript/axios.ts

@@ -230,7 +230,7 @@ const source: CancelTokenSource = axios.CancelToken.source();
 axios.get('/user', {
   cancelToken: source.token
 }).catch((thrown: AxiosError | Cancel) => {
-  if (thrown instanceof axios.Cancel) {
+  if (axios.isCancel(thrown)) {
     const cancel: Cancel = thrown;
     console.log(cancel.message);
   }