Adobe Extending Dreamweaver CS4 - Manual (Page 356)

350 EXTENDING DREAMWEAVER CS4
C-level extensibility
typedef JSBool (*JSNative)(JSContext *cx, JSObject *obj, unsigned int argc,
jsval *argv, jsval *rval)
Description
This function signature describes C-level implementations of JavaScript functions in the following situations:
• The cx pointer is a pointer to an opaque JSContext structure, which must be passed to some of the functions in
the JavaScript API. This variable holds the interpreter’s execution context.
• The obj pointer is a pointer to the object in whose context the script executes. While the script is running, the this
keyword is equal to this object.
• The argc integer is the number of arguments being passed to the function.
• The argv pointer is a pointer to an array of JSVal structures. The array is argc elements in length.
• The rval pointer is a pointer to a single JSVal structure. The function’s return value should be written to *rval .
The function returns JS_TRUE if successful; JS_FALSE otherwise. If the function returns JS_FALSE , the current script
stops executing and an error message appears.
JSBool JS_DefineFunction()
Description
This function registers a C-level function with the JavaScript interpreter in Dreamweaver. After the
JS_DefineFunction() function registers the C-level function that you specify in the call argument, you can invoke
it in a JavaScript script by referring to it with the name that you specify in the name argument. The name argument is
case-sensitive.
Typically, this function is called from the MM_Init() function, which Dreamweaver calls during startup.
Arguments
char *name , JSNative call, unsigned int nargs
• The name argument is the name of the function as it is exposed to JavaScript.
• The call argument is a pointer to a C-level function. The function must accept the same arguments as
readContentsOfFile , and it must return a JSBool , which indicates success or failure.
• The nargs argument is the number of arguments that the function expects to receive.
Returns
A Boolean value:
JS_TRUE indicates success; JS_FALSE indicates failure.
char *JS_ValueToString()
Description
This function extracts a function argument from a JSVal structure, converts it to a string if possible, and passes the
converted value back to the caller.
Note: Do not modify the returned buffer pointer. It can corrupt the data structures of the JavaScript interpreter. To
change the string, copy the characters into another buffer and create a JavaScript string.