Function with

pub fn with<V, F>(f: F) -> impl for<'cx> TryIntoJs<'cx, Value = V>
where
    V: Value,
    for<'cx> F: FnOnce(&mut Cx<'cx>) -> JsResult<'cx, V>,

Wraps a closure that will be lazily evaluated when TryIntoJs::try_into_js is called.

Useful for executing arbitrary code on the main thread before returning from a function exported with neon::export.

Note: The return type is JsResult. If you need to return a non-JavaScript type, call TryIntoJs::try_into_js.

See With for example usage.

Example

use std::time::Instant;

#[neon::export(task)]
fn sum(nums: Vec<f64>) -> impl for<'cx> TryIntoJs<'cx> {
    let start = Instant::now();
    let sum = nums.into_iter().sum::<f64>();
    let log = format!("sum took {} ms", start.elapsed().as_millis());

    extract::with(move |cx| -> NeonResult<_> {
        cx.global::<JsObject>("console")?
            .method(cx, "log")?
            .arg(&log)?
            .exec()?;

        sum.try_into_js(cx)
    })
}