Crate napi

High level Node.js N-API binding

napi-rs provides minimal overhead to write N-API modules in Rust.

Feature flags

napi1 ~ napi8

Because Node.js N-API has versions. So there are feature flags to choose what version of N-API you want to build for. For example, if you want build a library which can be used by node@10.17.0, you should choose the napi5 or lower.

The details of N-API versions and support matrix: n_api_version_matrix

tokio_rt

With tokio_rt feature, napi-rs provides a tokio runtime in an additional thread. And you can easily run tokio future in it and return promise.

use futures::prelude::*;
use napi::{CallContext, Error, JsObject, JsString, Result, Status};
use tokio;

#[napi]
pub async fn tokio_readfile(js_filepath: String) -> Result<JsBuffer> {
    ctx.env.execute_tokio_future(
        tokio::fs::read(js_filepath)
          .map(|v| v.map_err(|e| Error::new(Status::Unknown, format!("failed to read file, {}", e)))),
        |&mut env, data| env.create_buffer_with_data(data),
    )
}

latin1

Decode latin1 string from JavaScript using encoding_rs.

With this feature, you can use JsString.as_latin1_string function

serde-json

Enable Serialize/Deserialize data cross JavaScript Object and Rust struct.

#[derive(Serialize, Debug, Deserialize)]
struct AnObject {
    a: u32,
    b: Vec<f64>,
    c: String,
}

#[napi]
fn deserialize_from_js(arg0: JsUnknown) -> Result<JsUndefined> {
    let de_serialized: AnObject = ctx.env.from_js_value(arg0)?;
    ...
}

#[napi]
fn serialize(env: Env) -> Result<JsUnknown> {
    let value = AnyObject { a: 1, b: vec![0.1, 2.22], c: "hello" };
    env.to_js_value(&value)
}

Re-exports

• pub extern crate anyhow;
• pub extern crate tokio;
• pub use napi_sys as sys;

Modules

• bindgen_prelude
• iterator
• threadsafe_function

Structs

• AsyncCleanupHook
  Notice The hook will be removed if AsyncCleanupHook was dropped. If you want keep the hook until node process exited, call the AsyncCleanupHook::forget.
• AsyncWorkPromise
• CallContext
  Function call context
• CleanupEnvHook
  Created by Env::add_env_cleanup_hook And used by Env::remove_env_cleanup_hook
• Env
  Env is used to represent a context that the underlying N-API implementation can use to persist VM-specific state.
• Error
  Represent JsError. Return this Error in js_function, napi-rs will throw it as JsError for you. If you want throw it as TypeError or RangeError, you can use JsTypeError/JsRangeError::from(Error).throw_into(env)
• EscapableHandleScope
• ExtendedErrorInfo
• FinalizeContext
• JSON
• JsArrayBuffer
• JsArrayBufferValue
• JsBigInt
• JsBoolean
• JsBuffer
• JsBufferValue
• JsDataView
• JsDataViewValue
• JsDate
• JsDeferred
• JsError
• JsExternal
• JsFunction
• JsGlobal
• JsNull
• JsNumber
• JsObject
• JsRangeError
• JsString
• JsStringLatin1
• JsStringUtf8
• JsStringUtf16
• JsSymbol
• JsSyntaxError
• JsTimeout
• JsTypeError
• JsTypedArray
• JsTypedArrayValue
• JsUndefined
• JsUnknown
• NodeVersion
• Property
• PropertyAttributes
• PropertyClosures
• Ref

Enums

• Either
• KeyCollectionMode
• KeyConversion
• KeyFilter
• Status
• TypedArrayType
• ValueType

Traits

• NapiRaw
• NapiValue
• Task

Functions

• noop_finalize
  This function could be used for create_buffer_with_borrowed_data and want do noting when Buffer finalized.

Type Aliases

• Callback
• ContextlessResult
• Result

Attribute Macros

• module_init
  Marks a function or static variable as a library/executable constructor. This uses OS-specific linker sections to call a specific function at load time.