You can do it with casting. Execute JavaScript to return an array. The JS array must contain only one type, which must be primitive.
For example, execute a script which returns an array of Strings:
ArrayList<String> strings = (ArrayList<String>) js.executeScript(returnArrayOfStrings);
If you need an array of any other type, you can build it from those strings. For example, if you need an array of WebElements, design your JS to return locators, and then iterate through, finding elements and building a new array:
ArrayList<String> xpaths = (ArrayList<String>) js.executeScript(getLocators);
ArrayList<WebElement> elements = new ArrayList<WebElement>();
for (String xpath: xpaths){
element = driver.findElement(By.xpath(xpath));
elements.add(element);
}
You have the Array in Java, so you can keep it in memory when your tests go to different pages and still reference the Java Array,
The only catch is, if your JS array is changing on the client side, your Java Array won't automatically update itself (the jsexecuter only returns once per execution), but that's not a big deal - instead of referencing the Java Array directly, you can access it via a getter which first executes the JS again to get a new Array, which you can use to replace the previous one, or merge them etc, before returning the new/updated array to your test code.
