Can I execute a Javascript function inside Spidermonkey and get the return value?

Question

I'm just getting into using Delphi with Spidermonkey. Previously I would load a web page into a TWebBrowser component and interact with the Javascript code in the loaded web page. This was messy because to return values back to delphi I had to load them into a DOM object via the Javascript code and then inspect the DOM from Delphi to find that object and access it's value property.

With Spidermonkey, can I execute a specific Javascript function and get the return value easily and directly back into Delphi? If so, please point me to a quick code example that would be helpful. The 3 samples that came with Spidermonkey don't seem to get into this.

Don't know how in Delphi (I found only quite outdated bridge project and haven't tried it personally) but you're looking for the JS_CallFunctionName function, that can be used this way. — TLama
– TLama, Commented Sep 22, 2012 at 7:21
@TLama - Thanks again for finding the javascript bridge project. I still can't figure out how to get the return value directly since there is a layer of bridge class objects between code that uses the engine object and calling JS_CallFunctionName(). JS_CallFunctionName() is called internally by the main engine object for other purposes but doing that in a straightforward manner to simply execute one Javascript function and get the return value from it is not clear to me yet. For now I am creating a hidden TLabel component and using it to transfer the value from Javascript back to Delphi. — Robert Oschler
– Robert Oschler, Commented Sep 23, 2012 at 17:42

TLama · Accepted Answer · 2013-12-20 12:38:14Z

> With Spidermonkey, can I execute a specific Javascript function and get the return value easily and directly back into Delphi?

Yes, it possible. Sample compatible with Delphi XE2/XE4.

var
    recFunction,
    recReturnValue,
    recJSVar        : jsval;

........

//-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
//-=- Find entry point to function.
//-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

if JS_LookupProperty (TSMJSEngine.Context, TSMJSEngine.Global.JSObject, PAnsiChar (AnsiString (strFunctionToRun)), @recFunction) <> js_true then
begin
    //-=- Everything very bad :)
end;

if recFunction.asPtr = nil then
begin
    //-=- Everything very bad :)
end;

//-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
//-=- Call function 
//-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

if JS_CallFunctionValue (TSMJSEngine.Context, TSMJSEngine.Global.JSObject, recFunction, 0, nil, @recReturnValue) = Integer (false) then
begin
    //-=- Everything very bad :)
end;

//-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
//-=- Get returning result (type: string).
//-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

strResult := JSValToString (TSMJSEngine.Context, recReturnValue);

Rummy · Accepted Answer · 2013-05-22 20:17:46Z

0

I know nothing about delphi but it sounds like you are going to want to setup some type of api or routes for transferring between a frontend / backend system.

answered May 22, 2013 at 20:17

Rummy

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