How to pass an argument to evaluateJavaScript function?

Question

for (int i = 0; i < centerPointsList.size (); i++)
    {
        QVariant         holdInformation = map->page ()->mainFrame ()->evaluateJavaScript (QString ("constructFileName (%1).arg (centerPointsList[0].toFloat())"));
        QList <QVariant> allListObj      = holdInformation.toList ();
        QList <QVariant> fileNamesList   = allListObj[0].toList ();

        std :: cout << fileNamesList[0].toFloat() << "================= \n";

    }

This results in:

"SyntaxError: Parse error on line:1 Source:undefined"
Segmentation fault

I am guessing that the error is in the way I am passing the list item to the function evaluateJavaScript.

UPDATE:

I tried this:

for (int i = 0; i < centerPointsList.size (); i++)
 {
   QVariant holdInformation = map->page ()->mainFrame ()->evaluateJavaScript (QString ("constructFileName (%1)").arg (centerPointsList [0].toFloat ()));

which resulted in:

"TypeError: Result of expression 'centerPointFileName.split' [undefined] is not a function. on line:65 Source:file:///.../index.html"

The function constructFileName (in Javascript) is as follows:

function constructFileName (centerPointFileName)
 {
   var removeSpaces = centerPointFileName.split (" ");
   var fileNameWithoutSpaces = "", i;
   for (i = 0; i < removeSpaces.length; i++)
       fileNameWithoutSpaces = fileNameWithoutSpaces + removeSpaces [i];

Are you looking for `QString("constructFileName (%1)").arg(centerPointsList[0].toFloat())` ? — DCoder, Jan 05 '13 at 08:17

score 1 · Accepted Answer · answered Jan 05 '13 at 08:34

According to your update, your JavaScript function expects a string argument. The simplest approach should look like this:

QString info = QString("constructFileName('%1')").arg(centerPointsList[i].toFloat());
QVariant holdInformation = map->page()->mainFrame()->evaluateJavaScript(info);

However, in general this is not completely safe - if the interpolated argument %1 contains backslashes, double quotes or other special symbols, they need to be escaped first. I cannot comment on how that should be done, since I have never worked with Qt :)

How to pass an argument to evaluateJavaScript function?

1 Answers1