extracting strings from JavaScript code

Question

Using embedded SpiderMonkey in my C++ application I would like to extract all the strings from JavaScript code. JavaScript code looks something like this:

var foo = "something";  
var space = " ";  
var bar = foo + space + "beautiful";  

C++ code looks like this:

char *script = "var foo = \"something\"; var space = \" \"; var bar = foo + space + \"beautiful\";";
ok = JS_EvaluateScript(cx, global, script, strlen(script), filename, lineno, &rval);

So my questions is, after SpiderMonkey executes JavaScript, how can I extract the string from variable bar (extracted value should be "something beautiful") and use it in my regular C++ code? I guess I have to evaluate the script first and then somehow extract the string from the JavaScript variable. I don't know how to extract the string using SpiderMonkey.

My second question:
http://siliconforks.com/doc/parsing-javascript-with-spidermonkey/
This SpiderMonkey JavaScript parser is written for SpiderMonkey 1.6. How can this be done with latest SpiderMonkey, because APIs for parsing have changed?

Thnx in advance,
Goran

Answer 1

Since bar is property of global object, after the JS_EvaluateScript() I can use JS_GetProperty() function, something like this

JS_GetProperty(cx, global, "bar", &rval);
JSString *str = JS_ValueToString(cx, rval);
printf("%s\n", JS_EncodeString(cx, str));

Answer 2

Check String operation functions like subString. It can be used to resolve your query.