Get variable from web page with javascript in C++ Builder

Question

I have a MiFi modem (Huawei e5776) which comes with its own web page that displays total traffic per month. I want to extract this value and display a meter in the icon tray. I'm sure this is possible in C++ Builder (or Delphi) but even though I'm pretty experienced in using C++ Builder, I am not in anything web related. Can someone give me some pointers how to do this? I assume I need to run the script and then extract the variable somewhere, how do I do this?

Thanks.

PS: I'd add the contents of the page but can't see a way to attach a document. Here's the first few lines..

// JavaScript Document
var g_monitoring_traffic_statistics = null; 
var g_wlan_security_settings = null;
var g_wlan_basic_settings = null;
var g_connection_trafficresponse = null;
//Prefix string of ssid2 of Multi-SSID
var g_prefixWifiSsid = "ssid2_";

function getTrafficInfo(bit) {
    var final_number = 0;
    var final_str = "";
    if(g_monitoring_dumeter_kb > bit) {
        final_number = formatFloat(parseFloat(bit), 2);
        final_str = final_number + " B";
    }
    else if(g_monitoring_dumeter_kb <= bit && g_monitoring_dumeter_mb > bit) {
        final_number = formatFloat(parseFloat(bit) / g_monitoring_dumeter_kb, 2);
        final_str = final_number + " KB";
    }
    else if(g_monitoring_dumeter_mb <= bit && g_monitoring_dumeter_gb > bit) {
        final_number = formatFloat((parseFloat(bit) / g_monitoring_dumeter_mb), 2);
        final_str = final_number + " MB";
    }
    else if(g_monitoring_dumeter_gb <= bit && g_monitoring_dumeter_tb > bit) {
        final_number = formatFloat((parseFloat(bit) / g_monitoring_dumeter_gb), 2);
        final_str = final_number + " GB";
    }
    else {
        final_number = formatFloat((parseFloat(bit) / g_monitoring_dumeter_tb), 2);
        final_str = final_number + " TB";
    }
    return final_str;
}

Send the device an HTTP GET and then put the response into an HTML parser. — David Heffernan
– David Heffernan, Commented Sep 17, 2013 at 10:31
You can get javascript variables that way? I thought that would only work with html variables? Does GET also take care of running the script then? ::confused:: — Mike Versteeg
– Mike Versteeg, Commented Sep 17, 2013 at 10:39
OK, you are probably right. If the values only get filled out by execution of client side Javascript then you need a Javascript engine. So that's probably a headless webbrowser and some DOM access. — David Heffernan
– David Heffernan, Commented Sep 17, 2013 at 10:44

mh taqia · Accepted Answer · 2015-08-18 06:02:42Z

1

I suggest you to use a great html wrapper (named BCB HTML) for mshtml writed specially for C++Builder; With this wrapper you can execute java script inside C++ Builder cpp codes:

THTMLDocument document;
document.create();
document.write(
    "<html><body><script>"
        "function myFunc(n)"
        "{"
            "return n * n;"
        "}"
    "</script></body></html>");
document.parentWindow.execScript("alert(myFunc(3))", "javascript");

For your jscript:

String value = document.parentWindow.execScript("getTrafficInfo(1024)", "javascript");

Also it is possible to handle html events inside BCB, access html objects , ...

you can download it from here. To use this source add html.cpp to your project.

If you use TWebBrowser to load a html page, you need just define document in global scope and write below code to connect/attach document variable to WebBrowser1->Document:

void __fastcall TForm1::WebBrowser1DocumentComplete(TObject *ASender,
    const IDispatch *pDisp, const OleVariant &URL)
{
    document.documentFromVariant(WebBrowser1->Document);
    String value = document.parentWindow.execScript("getTrafficInfo(1024)", "javascript");
}

edited Aug 18, 2015 at 6:02

answered Sep 17, 2013 at 14:38

mh taqia

3,6361 gold badge27 silver badges37 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Mike Versteeg Over a year ago

Thanks! I'll give the version with TWebBrowser a try.

Collectives™ on Stack Overflow

Get variable from web page with javascript in C++ Builder

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related