Getting an empty JavaScript Array in Java (Selenium test)

Question

I need to get an empty array declared in a JavaScript script in a Java variable.

The JavaScript array is declared as so on a web page:

tc_vars["products"] = new Array();

(I only need the products's array, not the tc_vars one).

This is how I try to get this variable in Java :

Object[] value = (Object[]) js.executeScript("return tc_vars['products'];");

(Where js is a JavascriptExecutor associated with a Selenium WebDriver).

I usually have no trouble using this method for getting Strings, but it seems it just won't work for an empty Array. Moreover, I don't have any error message, the WebDriver just crashes.

The executeScript method returns an Object variable. Casting it to a String (when the JS variable is a String) works well, but I had no chance in casting this empty Array to String[] or Object[].

Answer 1

As I mentioned in my comment, you need to make sure you actually have access to tc_vars['products'] at the point which you want to test. E.g., manually open a browser, get to the point in the page where you would ask for that value using selenium, open devtools javascript console and check the value of tc_vars. If it's not available to you, it will not be available to the selenium webdriver.

Second thing is that for arrays, the selenium webdriver (at least the latest version: 2.42.2) returns ArrayList<Object> and not Object[]. so your cast should be:

ArrayList<Object> o = (ArrayList<Object>) js.executeScript("return tc_vars['products'];");