Release/v0.22.0 (#4107)

* fix/Avoid package.json import; (#4041)

* Added auto-generated config module `env/data.js` for importing package environment vars without importing the whole `package.json`;
Refactored `http.js` to use `env/data.js` instead of package.json;

* Added `env/data.js`;
Added `env/README.md`;

* Feat/export package version constant (#4065)

* Added auto-generated config module `env/data.js` for importing package environment vars without importing the whole `package.json`;
Refactored `http.js` to use `env/data.js` instead of package.json;

* Added `env/data.js`;
Added `env/README.md`;

* Export package version constant;

* Fixed cancelToken leakage; Added AbortController support; (#3305)

* Fixed cancelToken leakage;
Added AbortController support;

* Fixed typings;

* Documented `signal` option;

* Added processing of early cancellation using AbortController without sending a request;

Co-authored-by: Jay <jasonsaayman@gmail.com>

* Updating CI to run on release branches

* Fixed default transitional config for custom Axios instance; (#4052)

Refactored `/core/mergeConfig`;

Co-authored-by: Jay <jasonsaayman@gmail.com>

* Prepping v0.22.0 for release

* Updated date

Co-authored-by: Dmitriy Mozgovoy <robotshara@gmail.com>

lib/cancel/CancelToken.js

@@ -14,11 +14,42 @@ function CancelToken(executor) {
   }
 
   var resolvePromise;
+
   this.promise = new Promise(function promiseExecutor(resolve) {
     resolvePromise = resolve;
   });
 
   var token = this;
+
+  // eslint-disable-next-line func-names
+  this.promise.then(function(cancel) {
+    if (!token._listeners) return;
+
+    var i;
+    var l = token._listeners.length;
+
+    for (i = 0; i < l; i++) {
+      token._listeners[i](cancel);
+    }
+    token._listeners = null;
+  });
+
+  // eslint-disable-next-line func-names
+  this.promise.then = function(onfulfilled) {
+    var _resolve;
+    // eslint-disable-next-line func-names
+    var promise = new Promise(function(resolve) {
+      token.subscribe(resolve);
+      _resolve = resolve;
+    }).then(onfulfilled);
+
+    promise.cancel = function reject() {
+      token.unsubscribe(_resolve);
+    };
+
+    return promise;
+  };
+
   executor(function cancel(message) {
     if (token.reason) {
       // Cancellation has already been requested
@@ -39,6 +70,37 @@ CancelToken.prototype.throwIfRequested = function throwIfRequested() {
   }
 };
 
+/**
+ * Subscribe to the cancel signal
+ */
+
+CancelToken.prototype.subscribe = function subscribe(listener) {
+  if (this.reason) {
+    listener(this.reason);
+    return;
+  }
+
+  if (this._listeners) {
+    this._listeners.push(listener);
+  } else {
+    this._listeners = [listener];
+  }
+};
+
+/**
+ * Unsubscribe from the cancel signal
+ */
+
+CancelToken.prototype.unsubscribe = function unsubscribe(listener) {
+  if (!this._listeners) {
+    return;
+  }
+  var index = this._listeners.indexOf(listener);
+  if (index !== -1) {
+    this._listeners.splice(index, 1);
+  }
+};
+
 /**
  * Returns an object that contains a new `CancelToken` and a function that, when called,
  * cancels the `CancelToken`.