BriskBard, CEF4Delphi, WebView4Delphi, WebUI4Delphi and WebUI4CSharp

Posted: **Thu Apr 09, 2020 6:13 pm**

Hello,

What would be the best using CEF4 to capture the return of a javascript function executed on Chromium:

For example:

function sum (a, b) {
return a + b
}

what better way to get that return in Delphi?

Posted: **Fri Apr 10, 2020 6:39 am**

Hi,

Register a JavaScript extension to call custom functions that execute Delphi code. That code can send a process message to send any information to the browser process.

The JSExtension demo shows how to do all that. Read the code comments for all the details.

Posted: **Sat Apr 11, 2020 1:13 am**

you can use Chromium1ConsoleMessage

To output a message to the console on JS:
Form1.Chromium1.Browser.MainFrame.ExecuteJavaScript('var body =(myText);console.log("text="+body);', 'about:blank', 0);

Posted: **Sat Apr 11, 2020 9:40 pm**

zavet wrote: Sat Apr 11, 2020 1:13 am you can use Chromium1ConsoleMessage

To output a message to the console on JS:
Form1.Chromium1.Browser.MainFrame.ExecuteJavaScript('var body =(myText);console.log("text="+body);', 'about:blank', 0);

Yes, but I would not like to use the console, because it is running all the time in the application, I wanted something only when it was really the return of a js function

Posted: **Sun Apr 12, 2020 12:06 pm**

You can simply call JS: Alert( needed_result )
And intercept (and supress) this result in Jsdialog event

Posted: **Sun Apr 12, 2020 12:59 pm**

ForumReader wrote: Sun Apr 12, 2020 12:06 pm You can simply call JS: Alert( needed_result )
And intercept (and supress) this result in Jsdialog event

Nice trick!

Posted: **Mon Apr 13, 2020 4:43 pm**

salvadordf wrote: Sun Apr 12, 2020 12:59 pm
ForumReader wrote: Sun Apr 12, 2020 12:06 pm You can simply call JS: Alert( needed_result )
And intercept (and supress) this result in Jsdialog event
Nice trick!

what's the text size limit ?? if you know

Posted: **Mon Apr 13, 2020 4:58 pm**

shobits1 wrote: Mon Apr 13, 2020 4:43 pm
salvadordf wrote: Sun Apr 12, 2020 12:59 pm
ForumReader wrote: Sun Apr 12, 2020 12:06 pm You can simply call JS: Alert( needed_result )
And intercept (and supress) this result in Jsdialog event
Nice trick!
what's the text size limit ?? if you know

CEF4Delphi has the same limits as the Delphi strings (up to 2GB if you use unicode strings) but I don't know if CEF or Chromium has some other limit.

Posted: **Mon Apr 13, 2020 5:15 pm**

OK, thanks

I'll test it when I have time, it may make my code simpler instead of using callbacks from jsExtension, although I don't know how much it'll affect the CEF performance.

Posted: **Tue Apr 14, 2020 5:36 pm**

Limits for JS alert text is 10240byte

Code: Select all

let s = ''
for( i = 0; i < 1000*1000; i++){
    s += '.';
}
// in browser console
// s.length = 1,000,000

alert(s);

// delphi received  messageText  length = 10,240

Limit for JS prompt

Code: Select all

let s = '';
let s100 = '';
for( i = 0; i < 100; i++){
    s100 += '.';
}

for( i = 0; i < 1000*1000; i++){
    s += s100;
}

// in browser console
// s.length = 100,000,000

prompt(s, s);

// delphi received  messageText        length = 10,240
//                  defaultPromptText  length = 100,000,000

so alert has a limit to about 10KByte, prompt has the same limit on message(messageText), but no limit on value (defaultPromptText) tested up to 200,000,000 in length.

BriskBard, CEF4Delphi, WebView4Delphi, WebUI4Delphi and WebUI4CSharp

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