escargot/docs/Spec.md

Specification

Escargot is a lightweight JavaScript engine.
Escargot supports ECMAScript 2020 Specification and WebAssembly JavaScript Interface.

ECMAScript 2020 Specification

Implement ECMAScript 2020 standard (https://262.ecma-international.org/11.0/).

Unimplemented Features

• Atomics Object
• SharedArrayBuffer Object
• look-behind assertions

Escargot-Specific Features

Even though the features below are not part of ECMAScript standards, Escargot supports them for usability.
(These features are enabled only for standalone binary build)

Feature	Function
print (arg)	prints arg on stdout
load (fileName)	opens a file named fileName and executes the contents as source code
read (fileName)	opens a file named fileName and returns the contents as string
run (fileName)	opens a file named fileName, executes the contents as source code, and returns the time spent to execute the code
gc()	invokes garbage collector

WebAssembly JavaScript Interface

Implement WebAssembly JavaScript Interface (https://www.w3.org/TR/wasm-js-api-1/).

WebAssembly Core

Import WABT for WebAssembly core engine. WABT supports WebAssembly Core Specification.

Unimplemented Features

• Module.customSections

Code Caching Optimization

Support Code Caching method to accelerate the loading performance.
Code Caching stores the bytecode for the first time and reuses it when the same JavaScript code is executed again.
By reusing the bytecode, Code Caching could skip the parsing and compilation process which leads to fast loading time.