feat: resolve navigation page on navigation event (#624)

Allow passing in `resolveOnEvent`  (`navigatingTo` or `navigatedTo`) to `$navigateTo` options. When passed, an event listener will be attached to the page element, and whenever it fires - the Promise returned from `$navigateTo` will be resolved with the target `Page`. Useful for for triggering actions after a navigation is complete.

index.d.ts

@@ -9,7 +9,8 @@ export type NativeScriptVueItemEventData<T> = ItemEventData & { item: T }
 
 export interface NavigationEntryVue extends NavigationEntry {
     props?: Record<string, any>,
-    frame?: any
+    frame?: any,
+    resolveOnEvent?: Page.navigatingToEvent | Page.navigatedToEvent
 }
 
 export type navigateTo = (

platform/nativescript/plugins/navigator-plugin.js

@@ -89,6 +89,10 @@ export default {
 
         updateDevtools()
 
+        const resolveOnEvent = options.resolveOnEvent
+        // ensure we dont resolve twice event though this should never happen!
+        let resolved = false
+
         const handler = args => {
           if (args.isBackNavigation) {
             page.off('navigatedFrom', handler)
@@ -97,6 +101,17 @@ export default {
         }
         page.on('navigatedFrom', handler)
 
+        if (resolveOnEvent) {
+          const resolveHandler = args => {
+            if (!resolved) {
+              resolved = true
+              resolve(page)
+            }
+            page.off(resolveOnEvent, resolveHandler)
+          }
+          page.on(resolveOnEvent, resolveHandler)
+        }
+
         // ensure that the navEntryInstance vue instance is destroyed when the
         // page is disposed (clearHistory: true for example)
         const dispose = page.disposeNativeView
@@ -106,7 +121,10 @@ export default {
         }
 
         frame.navigate(Object.assign({}, options, { create: () => page }))
-        resolve(page)
+        if (!resolveOnEvent) {
+          resolved = true
+          resolve(page)
+        }
       })
     }
   }