Old thread but I had the same problem.
Found out that you can use string function Charindex to check if value is in array:
1. in Javascript code, store the content of the array as string in variable. For example vars.cities = ['London', 'Paris', 'Berlin'].join(',');
2. in Query activity, add a filtering condition
3. as the Expression of the filtering condition, enter Charindex($(vars/@cities) , @city)
4. as the Operator of the filtering condition, enter greater than or equal to
5. as the Value of the filtereing condition, enter 1
Now then the query is executed:
- if value of @city is found in the string of cities, value of 1 or greater is returned and the row is included in the result
- if value of @city is not found in the string of cities, value of 0 is returned and the row is not included in result