JavaScript Support

js-cgi provides full ES2023+ JavaScript support in a lightweight, embeddable runtime.

Supported Features

All standard ES2023+ language features are available:

• let, const, block scoping
• Arrow functions
• Template literals
• Destructuring (arrays and objects)
• Spread/rest operators
• Classes and inheritance
• Promises, async/await
• Generators and iterators
• Symbols
• Map, Set, WeakMap, WeakSet
• Proxy and Reflect
• BigInt
• Optional chaining (?.)
• Nullish coalescing (??)
• Array methods (.at(), .findLast(), .toSorted(), etc.)
• Object methods (Object.groupBy(), Object.hasOwn(), etc.)
• Regular expression improvements (lookbehind, named groups, /d flag)
• ES Modules (import/export)
• Top-level await (in module mode)

What's Not Available

js-cgi is a server-side CGI environment, not a browser or Node.js. The following are not available:

Browser APIs

• window, document, DOM
• fetch() — use the http extension instead
• localStorage, sessionStorage
• XMLHttpRequest
• Web Workers
• Canvas, WebGL

Node.js APIs

• require() — use ES modules or include()
• process, Buffer
• fs, path, os — use the file extension
• http/https modules — use the http extension
• crypto module — use the crypto extension
• npm packages

Timers

• setTimeout(), setInterval(), setImmediate()

Scripts execute synchronously from top to bottom. There is no event loop.

Available Built-in Objects

All standard JavaScript built-in objects work as expected:

• JSON — parse and stringify
• Math — mathematical operations
• Date — date and time
• RegExp — regular expressions
• Array, Object, String, Number, Boolean
• Map, Set, WeakMap, WeakSet
• Promise
• Error and subtypes
• ArrayBuffer, DataView, typed arrays

js-cgi Globals

In addition to standard JavaScript, js-cgi provides these globals:

Extensions add additional globals (sqlite, session, file, crypto, http) when loaded.