feat(overmind): allow immediate on reaction and change to nested option

Author: christianalfoni

packages/node_modules/overmind/src/index.ts

@@ -574,7 +574,9 @@ export class Overmind<ThisConfig extends IConfiguration>
             this.eventHub.emit(EventType.OPERATOR_ASYNC, execution)
             result.then(() => {
               execution.isRunning = false
-              mutationTree.dispose()
+              if (!boundExecution) {
+                mutationTree.dispose()
+              }
               this.eventHub.emit(EventType.OPERATOR_END, {
                 ...execution,
                 isAsync: true,
@@ -584,7 +586,9 @@ export class Overmind<ThisConfig extends IConfiguration>
             })
           } else {
             execution.isRunning = false
-            mutationTree.dispose()
+            if (!boundExecution) {
+              mutationTree.dispose()
+            }
             this.eventHub.emit(EventType.OPERATOR_END, {
               ...execution,
               isAsync: false,
@@ -829,20 +833,25 @@ export class Overmind<ThisConfig extends IConfiguration>
   reaction = (
     stateCallback: (state: ThisConfig['state']) => any,
     updateCallback: (state: ThisConfig['state']) => void,
-    deep: boolean = false
+    options: {
+      nested?: boolean
+      immediate?: boolean
+    } = {}
   ) => {
-    if (deep) {
+    let disposer
+
+    if (options.nested) {
       const value = stateCallback(this.state)
 
       if (!value || !value[IS_PROXY]) {
         throw new Error(
-          'You have to return an object or array when using a "deep" reaction'
+          'You have to return an object or array when using a "nested" reaction'
         )
       }
 
       const path = value[PATH]
 
-      return this.addFlushListener((mutations) => {
+      disposer = this.addFlushListener((mutations) => {
         mutations.forEach((mutation) => {
           if (mutation.path.startsWith(path)) {
             updateCallback(this.state)
@@ -856,10 +865,16 @@ export class Overmind<ThisConfig extends IConfiguration>
         () => updateCallback(tree.state)
       )
 
-      return () => {
+      disposer = () => {
         tree.dispose()
       }
     }
+
+    if (options.immediate) {
+      updateCallback(this.state)
+    }
+
+    return disposer
   }
   addMutationListener = (cb: IMutationCallback) => {
     return this.proxyStateTree.onMutation(cb)