Install Broadcasting Command Fix for Livewire Starter Kit (#55774)

* fix for livewire starter kit

* remove whitespace

* minimal style change

* Update BroadcastingInstallCommand.php

---------

Co-authored-by: Taylor Otwell <[email protected]>

Author: joshcirre

src/Illuminate/Foundation/Console/BroadcastingInstallCommand.php

@@ -116,6 +116,18 @@ public function handle()
                         trim($bootstrapScript.PHP_EOL.file_get_contents(__DIR__.'/stubs/echo-bootstrap-js.stub')).PHP_EOL,
                     );
                 }
+            } elseif (file_exists($appScriptPath = $this->laravel->resourcePath('js/app.js'))) {
+                // If no bootstrap.js, try app.js...
+                $appScript = file_get_contents(
+                    $appScriptPath
+                );
+
+                if (! str_contains($appScript, './echo')) {
+                    file_put_contents(
+                        $appScriptPath,
+                        trim($appScript.PHP_EOL.file_get_contents(__DIR__.'/stubs/echo-bootstrap-js.stub')).PHP_EOL,
+                    );
+                }
             }
         }