v4: MemoryStorageClient's DatasetClient stores records by reference #3812

let data = {
    rand: 0
};

async function refreshData() {
    data.rand = Math.random();
}

async function pushAndRead({ storageClient }: { storageClient: StorageClient }) {
    const dataset = await Dataset.open(null, { storageClient });
    refreshData();
    await dataset.pushData(data);
    refreshData();
    await dataset.pushData(data);
    refreshData();
    await dataset.pushData(data);

    console.log((await dataset.getData()).items);
}

await pushAndRead({ storageClient: new MemoryStorageClient() }); 
// memory storage client will print the same number three times, as all the items refer to the same object
/// [
///  { rand: 0.22326410406394825 },
///  { rand: 0.22326410406394825 },
///  { rand: 0.22326410406394825 }
/// ]

await pushAndRead({ storageClient: new FileSystemStorageClient() });
// file system client takes snapshots of the passed objects
/// [
///  { rand: 0.6922433682025506 },
///  { rand: 0.33313558872226434 },
///  { rand: 0.6864574308371908 }
/// ]