Pagination in DynamoDB using Node.js?

I've had a read through AWS's docs around pagination: http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/QueryAndScan.html#ScanQueryLimit

As their docs specify:

In a response, DynamoDB returns all the matching results within the scope of the Limit value. For example, if you issue a Query or a Scan request with a Limit value of 6 and without a filter expression, DynamoDB returns the first six items in the table that match the specified key conditions in the request (or just the first six items in the case of a Scan with no filter)

Which means that given I have a table called Questions with an attribute called difficulty(that can take any numeric value ranging from 0 to 2) I might end up with the following conundrum:

• A client makes a request, think GET /questions?difficulty=0&limit=3
• I forward that 3 to the DynamoDB query, which might return 0 items as the first 3 in the collection might not be of difficulty == 0
• I then have to perform a new query to fetch more questions that match that criteria without knowing I might return duplicates, since previously there was no LastEvaluatedKey given

How can I then paginate based on a query correctly? Something where I'll get as many results as I asked for whilst having the correct offset

via user2061811