Standardize JS API to encode/decode CBOR

[rmedaer]

Introduction

Concise Binary Object Representation, aka. CBOR (RFC 8949) is a data format widely deployed on the web. However there is no standardization of JS API to encode/decode it.

Use Cases

A consensus around a standard CBOR JS API specification might be used by web browsers or any other JS implementation to expose native CBOR support[^1].

Goals

The goal of this proposal is to define a standard JS API to encode/decode CBOR data format. It includes:

• the prototype of functions for encoding/decoding (based on know-how from existing JS implementations),
• the mapping and convertion between JS notation and CBOR representation considering the non-normative advices from RFC 8949 Section 6: "Converting Data between CBOR and JSON".

Non-goals

This proposal does not consider the RFC 8742: "Concise Binary Object Representation (CBOR) Sequences".

Proposed Solution

Based on existing implementations, the proposed solution defines the simple JS API of the form:

encoded = CBOR.encode(data) ➔ data = CBOR.decode(encoded)

Encoding CBOR

The CBOR.encode() method converts a JavaScript object or value to its CBOR representation in an ArrayBuffer object.

This method follow the recommendations from RFC 8949 Section 6.2: "Converting from JSON to CBOR " to encode JS types into CBOR representation.

Syntax

CBOR.encode(value)

Decoding CBOR

The CBOR.decode() method converts the CBOR representation within an ArrayBuffer object to a JavaScript object or value.

This method follow the recommendations from RFC 8949 Section 6.1: "Converting from CBOR to JSON" to decode JS types from CBOR representation.

Syntax

CBOR.decode(value)

Let’s Discuss

A few remaining questions:

• Is it the right place for this kind of proposal ?[^2]
• Should we map (some) CBOR tags to their equivalent in JS ? For instance date/time, URI,...

Previous discussion on discourse: https://discourse.wicg.io/t/proposal-native-cbor-or-messagepack-support/2011

[^1]: CBOR is already implemented in some browsers (Chrome, Firefox, and Edge) thanks to the new W3C Specification Web Authentication (WebAuthn). [^2]: Request for Mozilla Position has been asked here.