JSBool JS_SetElement()

Description Writes a single element of an array object.
Arguments JSContext *cx, JSObject *obj, unsigned int index, jsval *v
cx is the opaque JSContext pointer that was passed to the JavaScript function.
obj is a pointer to an array object.
index is an integer index into the array. The first element is index 0, and the last element is index (length - 1).
v is a pointer to a jsval whose contents should be copied to the jsval in the array.
Returns A Boolean value indicating success (JS_TRUE) or failure (JS_FALSE).