72 breaking releases

Uses new Rust 2021

new 0.73.0 Dec 1, 2022
0.72.0 Nov 24, 2022
0.71.0 Nov 16, 2022
0.56.0 Jul 28, 2022
0.1.0 Mar 26, 2021

#165 in Parser implementations

Download history 3253/week @ 2022-08-15 3625/week @ 2022-08-22 3934/week @ 2022-08-29 4022/week @ 2022-09-05 4450/week @ 2022-09-12 4639/week @ 2022-09-19 4453/week @ 2022-09-26 3409/week @ 2022-10-03 3937/week @ 2022-10-10 4725/week @ 2022-10-17 4335/week @ 2022-10-24 4401/week @ 2022-10-31 4700/week @ 2022-11-07 4811/week @ 2022-11-14 4475/week @ 2022-11-21 4418/week @ 2022-11-28

18,643 downloads per month
Used in 66 crates (6 directly)

MIT license

2.5K SLoC


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


~1.5M SLoC