Read Javascript variable from Web Browser control

Question

I am trying to read the value of a Javascript variable which is loaded and called from a WebBrowser control on my form.

Example:

index.html refers to a javas

Answer 1

To access global scope JavaScript variables, I used a custom method included here called GetGlobalVariable(). (It uses Document.InvokeScript from Juan's answer. +1)

Let's say your JavaScript variables created in the global scope like this:

var foo = "bar";
var person = {};
var person.name = "Bob";

Then you can access these values using the C# GetGlobalVariable() method like so. (You may need to set up a timer to continually check if the variables are populated.)

var foo = GetGlobalVariable(webBrowser, "foo");
var name = GetGlobalVariable(webBrowser, "person.name");

Here is the GetGlobalVariable() method. Notice it checks each part of variable reference to avoid an exception.

private object GetGlobalVariable(WebBrowser browser, string variable)
{
    string[] variablePath = variable.Split('.');
    int i = 0;
    object result = null;
    string variableName = "window";
    while  (i < variablePath.Length)
    {
        variableName = variableName + "." + variablePath[i];
        result = browser.Document.InvokeScript("eval", new object[] { variableName });
        if (result == null)
        {
            return result;
        }
        i++;
    }
    return result;
}