CosmosDB Random Document Stored Procedure

GetRandomDocument.js

function getRandomDocument(filterQuery){
    var collection = getContext().getCollection();
    var result = null;
    var count = 0;
    var pageSize = 50;

    function query(responseOptions) {
        return (filterQuery && filterQuery.length) ?
            collection.queryDocuments(collection.getSelfLink(), filterQuery, responseOptions, onReadDocuments) :
            collection.readDocuments(collection.getSelfLink(), responseOptions, onReadDocuments);
    }

    function getRandomInt(max) {
        return Math.floor(Math.random() * max);
    }

    function onReadDocuments(err, docFeed, responseOptions) {
        if (err) throw err

        if (docFeed)
            docFeed.forEach(function (doc) {
                if (getRandomInt(count++) === 0) {
                    result = doc;
                }
            });

        if (!responseOptions.continuation || !query(responseOptions)) {
            getContext().getResponse().setBody(result);
        }
    }

    if (!query({ pageSize: pageSize }))
        throw new Error("The query was not accepted by the server");
}