executing an async js method on the client

[shaharzi]

Hello,

Im new in cefsharp, im trying to execute an async method on our client with no success on the result.

example of code trying to execute:

window.query = async (args) => { const response = await fetch('https://jsonplaceholder.typicode.com/todos/1'); const todo = await response.json(); return todo; };

anything im trying from c#, the result not return.

any help with that?

thanks !

[amaitland]

You need to use EvaluateScriptAsPromiseAsync see https://github.com/cefsharp/CefSharp/wiki/General-Usage#2-how-do-you-call-a-javascript-method-that-returns-a-result

[shaharzi]

tried that and its not working

[ukandrewc]

I'm using that to return result of async functions, like this:

in .Net

Browser.ExecuteScriptAsync('wrapper()')

function myCallBack(result){
}

in JS:

async function wrapper(){
  r = await asyncFunction()
  MyObject.myCallBack(r)
}

[amaitland]

i'll be more specific. i want from c# to call a js method and get result. but the js method is with async.

Fundimendally an async function returns a promise. See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/async_function#return_value

but I'd suggest that you can't do that.

@ukandrewc You can using EvaluateScriptAsPromiseAsync

CefSharp/CefSharp.Test/OffScreen/OffScreenBrowserBasicFacts.cs

Line 294 in 4ef267c

[InlineData("var result = await fetch('./robots.txt'); return result.status;", true, "200")]

tried that and its not working

@shaharzi If you've made an attempt then you need to provide an example of what you have tried.

[ukandrewc]

@amaitland Thanks, I'll have a look at that, as it may be useful - still lots to learn ;-)

[shaharzi]

Eventually i used this approach and it worked

` public async Task EvaluateMacefScriptAsync(dynamic request, string methodName)
{
var script = WebBrowserExtensions.GetScriptForJavascriptMethodWithArgs(methodName,
new object[] {JsonConvert.SerializeObject(request)});

        var temp = await browser.EvaluateScriptAsPromiseAsync($"return await {script};");

        return temp;
    }`