It is possible to send JavaScript code to be executed on the client browser from a C++ module loaded on server.

Run JS code on client browser in Kudo Editor iframe

The JS code you want to execute on client can be sent from server to client as a string using WApplication’s doJavaScript function (SDK/Headers/wt_inc/Wt/WApplication). Your module needs to link against Wt lib located in SDK (SDK/Libraries/wt_lib/).

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The JS code is evaluated on client by calling window.eval() function before run and an exception will be thrown if it is not valid what will cause a client disconnect.

Post a message

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You can use this mechanism and run JavaScript code that will post a message from iframe to its parent. There are two ways to send a message:

Via ‘xepstm_to_p’ event

Create a xepstm_to_p event with two members _m for message name and _mc for message content.

XeUpdateLock lock;
if (lock)
{
    std::string js = "{"
        "var event = document.createEvent('Event');"
        "event.initEvent('xepstm_to_p', true, true);"
        "event._m = messageName;"
        "event._mc = messageContent;"
        "window.dispatchEvent(event);"
        "}";
    Wt::WApplication::instance()->doJavaScript(js);
}

messageName and messageContent are arbitrary strings.

This will send a JSON message like this to parent frame:

{
    messageName: messageName,
    message: messageContent
}

Using postMessage

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from Kudo Editor iframe to Partner Web Application

It is possible to post data from Kudo Editor iframe to the Partner Web Application directly on the client browser. A Partner Web Applications is referred as “parent” in our SDK.

Using our SDK

Our SDK provides two convenient C++ functions for the communication from Kudo Editor loaded in an iframe to a Partner Web Application, see API Reference.

void XeIntegration::postStringToParent( std::string message );
void XeIntegration::postJSONMessageToParent( std::string messageName, std::string messageContent );

We also provide a ready-to-go example application “CrossOriginIntegration”, see samples. This example is a custom module that can be loaded by Kudo Server. 

Using postMessage

In addition to the helper functions, the Web API function “Window.postMessage()” can be used directly in your module. For that, JavaScript code executing this function must be transferred from Kudo Server to the client browser. 

Sending a simple string from the Kudo Server to its iframe and from there to the parent (your web application) looks like this:

XeUpdateLock lock;
if (lock)
{
    std    std::string js = "if (window.parent) {"
                                                  "window.parent.postMessage("my message", '*');"
                                          "}";
    Wt    Wt::WApplication::instance()->doJavaScript(js);
}