Paginating in AWS SDK

Pagination utilities to the rescue!

Luckily for us, Amazon have taken care of this for us in the JavaScript SDK v3, providing a set of pagination utilities that greatly simplify the task. For example:

For most of the API operations, there is now a paginator pattern implemented, with the prefix ‘paginate’, making the pattern paginate<operation> - for example:

• S3: List objects with paginateListObjectsV2
• DynamoDb: Query items with paginateQuery
• SSM: List Parameters with paginateDescribeParameters

Using it is easy, the paginators return an AsyncIterator, so we can just loop over it as follows:

const paginator = paginateListObjectsV2(paginationConfig, params);
 
const contents: _Object[] = [];
for await (const page of paginator) {
  contents.push(...page.Contents);
}

The paginationConfig parameter allows us to specify things like the page size and the startingToken

That’s it - no more boiler plate, and less scope for bugs to creep in!

Further reading

It’s worth reading up on async generator functions to understand how this has been implemented.

There’s similar functionality in the other SDKs too, for example php, python, java, perhaps the Javascript documentation is just lacking.