Return function JavaScrit in Delphi

[EdsonAlves]

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?

[salvadordf]

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.

[zavet]

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);

[EdsonAlves]

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

[ForumReader]

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

[salvadordf]

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

Nice trick!

[shobits1]

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

[salvadordf]

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.

[shobits1]

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.

[shobits1]

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.