How to use the EvaluateJavaScriptAsync() method for a JS function that returns a promise?

Question

I need to access the result of a promise that is returned from a javascript function. To access this function I using the WebView component and the EvaluateJavaScriptAsync() function; But the function always returns empty and too quickly, while in the browser it returns correctly. Does MAUI not support this type of request in JS?

Answer 1

the return value from EvaluateJavaScriptAsync() is the promise and not the result of the promise resolve. javascript has no method to turn an async call to sync.

if you have hooked up javascript calling your .net code, then add to code

await webview.EvaluateJavaScriptAsync("dotask().then(r => callDotNet(r));

or you can poll:

await webview.EvaluateJavaScriptAsync("window.result = ''; dotask().then(r => window.result = r"));
var result = await webview.EvaluateJavaScriptAsync("window.result");
while(result == "")
{
   Thread.Sleep(10);
   result = await webview.EvaluateJavaScriptAsync("window.result");
}