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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.//!  This example shows you how to evaluate JavaScript expression and deserialize//!  return value into a Rust object.
// NOTE:// Here we are deserializing to `serde_json::Value` but you can// deserialize to any other type that implementes the `Deserialize` trait.
use deno_core::v8;use deno_core::JsRuntime;use deno_core::RuntimeOptions;
fn main() {  let mut runtime = JsRuntime::new(RuntimeOptions::default());
  // Evaluate some code  let code = "let a = 1+4; a*2";  let output: serde_json::Value =    eval(&mut runtime, code).expect("Eval failed");
  println!("Output: {:?}", output);
  let expected_output = serde_json::json!(10);  assert_eq!(expected_output, output);}
fn eval(  context: &mut JsRuntime,  code: &str,) -> Result<serde_json::Value, String> {  let res = context.execute_script("<anon>", code);  match res {    Ok(global) => {      let scope = &mut context.handle_scope();      let local = v8::Local::new(scope, global);      // Deserialize a `v8` object into a Rust type using `serde_v8`,      // in this case deserialize to a JSON `Value`.      let deserialized_value =        serde_v8::from_v8::<serde_json::Value>(scope, local);
      match deserialized_value {        Ok(value) => Ok(value),        Err(err) => Err(format!("Cannot deserialize value: {:?}", err)),      }    }    Err(err) => Err(format!("Evaling error: {:?}", err)),  }}