#serde #v8 #serialization #deserialization #rusty-v8


Rust to V8 serialization and deserialization

16 releases (breaking)

new 0.11.0 Sep 13, 2021
0.9.3 Aug 23, 2021
0.8.0 Jul 2, 2021
0.1.0 Mar 26, 2021
Download history 976/week @ 2021-05-26 1445/week @ 2021-06-02 2405/week @ 2021-06-09 3563/week @ 2021-06-16 3479/week @ 2021-06-23 3555/week @ 2021-06-30 4472/week @ 2021-07-07 3251/week @ 2021-07-14 3422/week @ 2021-07-21 2925/week @ 2021-07-28 3160/week @ 2021-08-04 4203/week @ 2021-08-11 3909/week @ 2021-08-18 3179/week @ 2021-08-25 2999/week @ 2021-09-01 3816/week @ 2021-09-08

15,059 downloads per month
Used in 29 crates (2 directly)

MIT license



Author: Aaron O'Mullan aaron.omullan@gmail.com

Serde support for encoding/decoding (rusty_)v8 values.

Broadly serde_v8 aims to provide an expressive but ~maximally efficient encoding layer to biject rust & v8/js values. It's a core component of deno's op-layer and is used to encode/decode all non-buffer values.

Original issue: denoland/deno#9540


serde_v8 fits naturally into the serde ecosystem, so if you've already used serde or serde_json, serde_v8's API should be very familiar.

serde_v8 exposes two key-functions:

  • to_v8: maps rust->v8, similar to serde_json::to_string, ...
  • from_v8: maps v8->rust, similar to serde_json::from_str, ...

Best practices

Whilst serde_v8 is compatible with serde_json::Value it's important to keep in mind that serde_json::Value is essentially a loosely-typed value (think nested HashMaps), so when writing ops we recommend directly using rust structs/tuples or primitives, since mapping to serde_json::Value will add extra overhead and result in slower ops.

I also recommend avoiding unecessary "wrappers", if your op takes a single-keyed struct, consider unwrapping that as a plain value unless you plan to add fields in the near-future.

Instead of returning "nothing" via Ok(json!({})), change your return type to rust's unit type () and returning Ok(()), serde_v8 will efficiently encode that as a JS null.

Advanced features

If you need to mix rust & v8 values in structs/tuples, you can use the special serde_v8::Value type, which will passthrough the original v8 value untouched when encoding/decoding.


  • Experiment with KeyCache to optimize struct keys
  • Experiment with external v8 strings
  • Explore using json-stringifier.cc's fast-paths for arrays
  • Improve tests to test parity with serde_json (should be mostly interchangeable)
  • Consider a Payload type that's deserializable by itself (holds scope & value)
  • Ensure we return errors instead of panicking on .unwrap()s


~1M SLoC