Crate quickjs_wasm_rs

High-level bindings and serializers for a Wasm build of QuickJS.

Bindings

JSContextRef corresponds to a QuickJS JSContext and JSValueRef corresponds to a QuickJS JSValue.

use quickjs_wasm_rs::JSContextRef;
let mut context = JSContextRef::default();

will create a new context.

Callbacks

To create a callback to be used in JavaScript, use wrap_callback:

use quickjs_wasm_rs::js_value::JSValue;
let context = JSContextRef::default();
let callback = context.wrap_callback(|_ctx, _this, args| {
   let s = args[0].to_string();
   println!("{}", s);
   Ok(JSValue::Undefined)
})?;
let global = context.global_object()?;
global.set_property("print", callback)?;

Converting to and from Rust types

When working with callbacks, it is often useful to convert to Rust types.

_this and args in the callback function are of type JSValueRef which can be converted into JSValue. JSValue supports try_into to convert to Rust types.

Rust types can then be converted back to JSValue using try_into.

use quickjs_wasm_rs::js_value::JSValue;

ctx.wrap_callback(|_ctx, this, args| {
    let this: std::collections::HashMap<String, JSValue> = this.try_into()?;
    let first_arg: Vec<JSValue> = args[0].try_into()?;
    let ret_val = 0;
    Ok(ret_val.try_into()?)
})?;

Serializers

This crate provides optional transcoding features for converting between serialization formats and JSValueRef:

• messagepack provides quickjs_wasm_rs::messagepack for msgpack, using rmp_serde.
• json provides quickjs_wasm_rs::json for JSON, using serde_json. msgpack example:

use quickjs_wasm_rs::{messagepack, JSContextRef, JSValueRef};
let context = JSContextRef::default();
let input_bytes: &[u8] = ...;
let input_value = messagepack::transcode_input(&context, input_bytes).unwrap();
let output_value: JSValueRef = ...;
let output = messagepack::transcode_output(output_value).unwrap();

Structs

• Deserializer
  Deserializer is a deserializer for JSValueRef values, implementing the serde::Deserializer trait.
• Exception
  Exception represents a JavaScript exception that occurs within the QuickJS context.
• JSContextRef
  JSContextRef is a wrapper around a raw pointer to a QuickJS JSContext.
• JSValueRef
  JSValueRef is a wrapper around a QuickJS JSValue with a reference to its associated JSContextRef.
• Serializer
  Serializer is a serializer for JSValueRef values, implementing the serde::Serializer trait.

Enums

• JSError
  JSError represents various types of JavaScript errors that can occur during the execution of JavaScript code in QuickJS.
• JSValue
  A safe and high level representation of a JavaScript value.

Functions

• from_qjs_value
  Converts a reference to QuickJS value represented by quickjs_wasm_rs::JSValueRef to a JSValue.
• to_qjs_value
  Converts a reference to a JSValue to a quickjs_wasm_rs::JSValueRef.