# napi-derive
## js_function
```rust
#[macro_use]
extern crate napi_derive;
use napi::{CallContext, Error, JsNumber, JsUnknown, Module, Result, Status};
use std::convert::TryInto;
#[module_exports]
fn init(mut exports: JsObject) -> Result<()> {
exports.create_named_method("testThrow", test_throw)?;
exports.create_named_method("fibonacci", fibonacci)?;
Ok(())
}
#[js_function]
fn test_throw(_ctx: CallContext) -> Result {
Err(Error::from_status(Status::GenericFailure))
}
#[js_function(1)]
fn fibonacci(ctx: CallContext) -> Result {
let n = ctx.get::(0)?.try_into()?;
ctx.env.create_int64(fibonacci_native(n))
}
#[inline]
fn fibonacci_native(n: i64) -> i64 {
match n {
1 | 2 => 1,
_ => fibonacci_native(n - 1) + fibonacci_native(n - 2),
}
}
```