This page states that to read a single item you provide the id to the item class:
await container.item("1").read();
And yet, after many hours of my life, I stumbled upon this issues thread:
##9788
In which southpolesteve kindly points out that you should in fact use item(id, id) if the id is the partition key. When creating a container in the portal it is a requirement to add a partition key, so I believe this is a mandate? If not, please, please, please, update this documentation to reflect that you may need to add the id twice. I beg of you. Save future developers this pain.

Document Details

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• ID: c4bed5dc-c173-b7b9-f52d-a4ead58e15c0
• Version Independent ID: 27ed24eb-b98a-7c2d-dd29-23893ab38b74
• Content: Azure Cosmos DB client library for JavaScript
• Content Source: docs-ref-services/latest/cosmos-readme.md
• Service: cosmosdb
• GitHub Login: @kushagraThapar
• Microsoft Alias: kuthapar