Evaluate JavaScript from Qt source

moravas

Hi Folks,

can anybody explain me, how I can execute javascript from a command line application? As I saw, some QWebWidget or something like that is needed on some UI interface.
My problem is that I would like to put some algorithm into separated javascript file due to portability and evaluate it, but I don't like any UI.

Regards,
Norbert

sierdzio

You can evaluate it using QtScript module.

moravas

Hi,

thank you fort the short reply. I tried out, without too much success. I have the following sample JS function in separated file:

.pragma library
function func() {
    return 2 * 8;
}

and the following C++ code:

    QFile scriptFile("://compiler.js");
    scriptFile.open(QIODevice::ReadOnly);
    QString script(scriptFile.readAll());
    scriptFile.close();

    qDebug() << script;

    QScriptEngine myEngine;
    QScriptValue retVal = myEngine.evaluate(script, "://compiler.js");
    qDebug() << retVal.toString();

but I'm getting the error: "SyntaxError: Parse error". Could you point me, what did I wrong?

Regards,
Norbert

p.s.: sorry for the wrong highlight, I'm new to this forum design.

sierdzio

I have not used QtScript myself, sorry. One thing that might help is to open the file in this mode: QFile::ReadOnly | QFile::Text

Hi @moravas,

.pragma library

is QML-only syntax. You can't use this with Qt Script.

moravas

Hi,

thank you for the help, it solved the issue. The result is "undefined" now. I don't udnerstand, but I think, it's regarding to another topic.

Regards.

The result is undefined now, because your javascript contains only a function definition. Everything works fine and undefined is the correct result. If you want to receive something else, try for example:

function func() {
return 2 * 8;
}
func() // actually call func()